WO2017112559A1 - Methods and systems for generating a renewable drop-in fuels product - Google Patents

Abstract

Methods and systems for utilizing renewable energy, including nuclear, hydroelectric, wind, geothermal, and solar, to power electrochemical conversion of carbon dioxide to various reduced compounds including methanol and/or glycols, which can be condensed to form drop-in fuel compounds. A method may include providing a divided electrochemical cell comprising an anode compartment, a cathode, and an electrolyte; providing an aqueous solution of a reducible sugar and an alkali metal salt as electrolyte into the cathode compartment; providing electrical energy from an energy source selected from the group consisting of nuclear, hydroelectric, wind, geothermal, and solar power to the electrochemical cell to reduce said sugar to a polyhydric alcohol; and contacting the polyhydric alcohol with a solid acid condensation catalyst.

Description

METHODS AND SYSTEMS FOR GENERATING A RENEWABLE DROP- IN FUELS PRODUCT

The present application claims the benefit of pending U.S. Provisional Patent Application Serial No. 62/270,686, filed 22 December 2015.

Technical Field of the Invention

Embodiments of the present disclosure generally relate to methods and systems for generating a renewable drop-in fuels product, particularly through electrochemically converting carbon dioxide to polyols, which can be reacted to form a drop-in fuels product.

Background of the Invention

This section is intended to introduce various aspects of the art, which may be associated with exemplary embodiments of the present invention. This discussion is believed to assist in providing a framework to facilitate a better understanding of particular aspects of the present invention. Accordingly, it should be understood that this section should be read in this light, and not necessarily as admissions of any prior art.

Development of fossil fuel alternatives derived from renewable resources have received recent attention. While cellulosic biomass has garnered particular attention in this regard due to its abundance and the versatility of the various constituents found therein, particularly cellulose and other carbohydrates, the development and implementation of bio-based fuel technology has been slow. Existing technologies have produced fuels having a low energy density (e.g., bioethanol) and/or that are not fully compatible with existing engine designs and transportation infrastructure (e.g., methanol, biodiesel, Fischer- Tropsch diesel, hydrogen, and methane). Moreover, conventional bio-based processes have typically produced intermediates in dilute aqueous solutions (>50% water by weight) that are difficult to further process. As such, production of fuel blends having similar compositions to fossil fuels (drop-in fuel products) from renewable resources is desirable.

While there have been development in processing cellulosic biomass into drop-in fuel products, such development has its own challenges, such as conducting hydrothermal reactions that require high pressure equipment that can be challenging to operate. Further, in addition to the desired carbohydrates, other substances may be present within cellulosic biomass that can be especially problematic to deal with in an energy- and cost-efficient manner in hydrothermal reactions. For example, during cellulosic biomass processing, the significant quantities of lignin present in cellulosic biomass may lead to fouling of processing equipment, potentially leading to costly system down time.

As evidenced by the foregoing, there is still a need for development of methods and systems to produce drop-in fuel products from a renewable energy source that does not involve hydrothermal reactions of cellulosic biomass materials. Summary of the Invention

Accordingly, the present disclosure describes systems and methods for producing fuel blends having similar compositions to fossil fuels from renewable energy sources and carbon dioxide, where hydrothermal reactions of cellulosic biomass material is not necessary.

In the present disclosure, there is provided a method comprising: (a) providing a divided electrochemical cell comprising an anode in a first cell compartment and a cathode in a second cell compartment, wherein the electrochemical cell comprises an electrolyte; (b) providing an aqueous solution of a reducible sugar and an alkali metal salt as electrolyte into the second compartment; (c) providing electrical energy from an energy source selected from the group consisting of nuclear, hydroelectric, wind, geothermal, and solar power to the electrochemical cell to apply an electrical potential between the anode and the cathode and through said sugar solution to reduce said sugar to a polyhydric alcohol; (d) contacting the polyhydric alcohol with a solid acid condensation catalyst at a temperature in the range from 325 °C to about 425 °C to produce water and an aromatics-rich higher molecular weight hydrocarbons stream having at least 50wt% of aromatics containing hydrocarbon based on the aromatics-rich high molecular weight hydrocarbons stream.

The method can further comprise generating the reducible sugar, wherein said generating step comprises: providing a divided electrochemical cell comprising an anode in a first cell compartment and a cathode in a second cell compartment, wherein the electrochemical cell comprises an electrolyte; providing a biomass substrate to the first compartment; and providing electrical energy from an energy source selected from the group consisting of nuclear, hydroelectric, wind, geothermal, and solar power to the electrochemical cell to apply an electrical potential between the anode and the cathode sufficient to at least partially degrade the substrate to generate a reducible sugar.

The method can further comprise, prior to step (d), reacting the polyhydric alcohol with an acidic amorphous silica alumina catalyst at a temperature in the range from 300°C to 400°C to generate a mono-oxygenate, thereby producing a mono-oxygenated stream containing water and organic monooxygenates having a boiling point of at least 40°C; optionally condensing the monooxygenated stream to liquid phase; wherein step (d) comprises contacting the mono-oxygenated stream with a solid acid condensation catalyst at a temperature in the range from 325 °C to about 425 °C producing water and an aromatics-rich higher molecular weight hydrocarbons stream having at least 50wt% of aromatics containing hydrocarbon based on the aromatics-rich high molecular weight hydrocarbons stream.

Other advantages and features of embodiments of the present invention will become apparent from the following detailed description. It should be understood, however, that the detailed description and the specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

Brief Description of the Drawings

The following figures are included to illustrate certain aspects of the present disclosure, and should not be viewed as exclusive embodiments. The subject matter disclosed is capable of considerable modifications, alterations, combinations, and equivalents in form and function, as will occur to one having ordinary skill in the art and the benefit of this disclosure.

FIGS. 1A and IB depict a block diagram of an illustrative embodiment of a system to electrochemically convert carbon dioxide to glycols;

FIG. 2 is a flow diagram of an illustrative embodiment of a method to electrochemically produce a reaction product from carbon dioxide;

FIG. 3 is a flow diagram of another illustrative embodiment of a method to electrochemically produce a reaction product from carbon dioxide; FIG. 4 is a flow diagram of an illustrative embodiment of using solar energy to power electrochemical conversion of carbon dioxide to generate drop-in fuels components.

FIG. 5 is a GC trace of the glycol-containing feed mixture to Example 2. FIG. 6 is a GC trace of an organic layer from the monooxygenated stream from Example 2.

FIG. 7 is a GC trace of a reaction product after contacting the monooxygenates with ZSM-5 from Example 3.

FIG. 8 a gas chromatograph (GC) of a diesel produced according to Example 5.

FIG. 9 is a gas chromatography of a commercial no. 2 standard diesel.

Detailed Description of the Invention

Solar power systems that employ photovoltaic cells to convert the radiant energy of sunlight directly into electrical energy are well known in the art. Exemplary disclosures include U.S. Patent Publication No. US20120256490, which relates to solar electrical generators that can be directly connected to existing utility power grids, or U.S. Patent Nos. 8792227, 8797719, or 8816528, which relate to use of photovoltaic cells in portable systems. The electric energy from solar energy can be used in electrochemical reductions of carbon dioxide to an intermediate oxygenated compound that can be further processed into a fuels product. It is understood that the electrical energy for the electrochemical reduction of carbon dioxide can additionally or alternatively come from other sources, including nuclear, hydroelectric, wind, or geothermal.

In some embodiments, the electrical energy from solar energy can be used to electrochemically reduce carbon dioxide to methanol. The electrical energy generated from solar energy may be applied to electrochemical cell or the cell may be a photo-electrochemical cell. The carbon dioxide may be obtained from any source (e.g., an exhaust stream from fossil-fuel burning power or industrial plants, from geothermal or natural gas wells or the atmosphere itself). Most suitably, the carbon dioxide may be obtained from concentrated point sources of generation prior to being released into the atmosphere. For example, high concentration carbon dioxide sources may frequently accompany natural gas in amounts of 5% to 50%, exist in flue gases of fossil fuel (e.g., coal, natural gas, oil, etc.) burning power plants, and high purity carbon dioxide may be exhausted from cement factories, from fermenters used for industrial fermentation of ethanol, and from the manufacture of fertilizers and refined oil products. Certain geothermal steams may also contain significant amounts of carbon dioxide. The carbon dioxide emissions from varied industries, including geothermal wells, may be captured on-site. Thus, the capture and use of existing atmospheric carbon dioxide in accordance with some embodiments of the present invention generally allow the carbon dioxide to be a renewable and essentially unlimited source of carbon.

In some embodiments, carbon dioxide reduction is achieved via a gas phase electrochemical reduction as disclosed in WO2013102086 through the use of a proton exchange membrane (PEM) fuel cell comprising an anode that is a gas diffusion electrode and a cathode that is a chemically modified gas diffusion electrode with a coating of a polymer aromatic amine. The disclosure of WO2013102086 is incorporated herein by reference. A gas phase fuel is introduced to the anode. The electrical energy from solar and carbon dioxide in gas phase are applied to the cathode to reduce the carbon dioxide to a product comprising methanol. The coating of polymer aromatic amine can be pyridinium- containing polymer, particularly 4- polyvinylpyridine. The coating on either the anode or cathode can include a metal nanoparticle on carbon gas diffusion electrode. Such method can provide between approximately 30% to 95% faradaic yield for methanol.

In preferred embodiments, the PEM fuel cell may be a 5 cm2 PEM single cell fuel cell employing serpentine flow fields (e.g., a cathode flow field and a separate anode flow field). The fuel cell is generally operational for gas phase electrochemical reduction of carbon dioxide to an organic product mixture including methanol, propanol, and the like. The reduction generally takes place by introducing humidified carbon dioxide into a cathode flow field and introducing hydrogen (H2) into an anode flow field. The fuel cell further includes a separator or membrane between the cathode and anode. The separator (or membrane) may include a membrane electrode assembly (MEA) positioned between the anode and the cathode.

The gas phase fuel introduced to the anode can be hydrogen. The fuel may alternatively implement the oxidation of water to oxygen at the anode in place of hydrogen. In a particular implementation, humidified hydrogen at approximately 90° C is introduced to the anode. Likewise, humidified carbon dioxide at approximately 90° C can be introduced to the cathode. Various embodiments include an organic product and/or inorganic product extractor to extract or separate one or more of the products for the reduction of carbon dioxide.

In some embodiments, different catalysts are used in the electrochemical cell to generate methanol from carbon dioxide via reduction to carbon monoxide and hydrogen, which react with one another to produce methanol, as disclosed in US20090014336, the disclosure of which is herein incorporated by reference. In particular, the method can include electrochemically reducing the carbon dioxide in a divided electrochemical cell that includes an anode in one cell compartment and a metal cathode electrode in another cell compartment that also contains an aqueous solution or aqueous methanolic solution and an electrolyte of one or more alkyl ammonium halides, alkali carbonates or combinations thereof. The reduction produces therein a reaction mixture containing carbon monoxide and hydrogen which can be subsequently used to produce methanol while also producing oxygen in the cell at the anode. The electrolyte can include one or more multi- alkyl ammonium halides, one or more alkali carbonates or bicarbonates and methanol or water. The multi-alkyl ammonium halide(s) include tetrabutylammonium halide(s), such as tetrabutylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium iodide or mixtures thereof. The alkali carbonates include sodium or potassium bicarbonates. The metal electrode can be a Cu, Au, Ag, Zn, Pd, Ga, Ni, Hg, In, Sn, Cd, Tl, Pb or Pt electrode.

It had been noted that electrochemical reduction of C02 using noble metal, preferentially a gold electrode as a catalyst in aqueous methanol (or in water) with tetrabutylammonium halides and alkali carbonates as electrolytes not only gives CO but also H2 at the cathode, while producing oxygen gas (02) at the anode, as shown in the equation below:

C02 + 2H20→CO + 2H2 (at the cathode) and 3/2 02 (at the anode)

The CO and H2 produced at the cathode are subsequently reacted over Cu and Ni based catalysts to produce high yields of methanol (CH30H), as shown in the equation below:

CO + 2H2→ CH30H The specific conditions for the above-described chemical reactions are generally known to skilled chemists and optimum conditions can be readily established for the reactions. Typical yields are about 60 to 100%, based on the amount of C02, preferably about 75 to 90%, and more preferably about 85 to 95%. At a proper voltage, i.e. about -1.5 to -4 V with respect to an Ag/AgCl electrode, a ratio of about 1:2 of CO and H2 can be produced with good coulombic efficiency at the cathode. The electrochemical reduction of C02 can also be achieved efficiently using KHC03 as the electrolyte in aqueous medium. C02 is readily reduced in the aqueous medium over gold electrode to an optimal 1:2 (CO to H2) ratio at the cathode at -3.2V.

In some other embodiments, the carbon dioxide can be in an aqueous solution as disclosed in U.S. Patent No. 4609441, the disclosure if which is incorporated herein by reference. In particular, a solution of carbon dioxide in an aqueous solvent having electrolytes dissolved therein can be electrochemically reduced to methanol using a molybdenum cathode. The reduction of carbon dioxide to methanol is represented by the equation:

C02 + 6H+ + 6e- <→ CH30H + H20

As described, a molybdenum cathode can reduce carbon dioxide to methanol selectively and with up to 80 to 100% faradaic efficiency. Such reductions can occur, for example, at -0.7 V vs. SCE at pH 4.2, only 160 mV negative of the standard potential corrected for pH. The pH of the solution should fall within the range from about 0 to about 7. If the pH is in the range from about 5 to about 7, it is necessary to have an added electrolyte. If the pH is below about 5, the acid provides sufficient electrolyte. Generally, the cathode is controlled to have a voltage from about -0.5 V to about -1.1 V relative to saturated calomel electrode (SCE), which is a reference electrode.

In other embodiments, as disclosed by U.S. Patent No. 8592633, the disclosure of which is incorporated herein by reference, carbon dioxide can be electrochemically reduced to generate a carboxylate that can be acidified to form a carboxylic acid, which is then contacted with hydrogen to form a reaction product that includes at least one of formaldehyde, methanol, glycolic acid, glyoxal, glyoxylic acid, glycolaldehyde, ethylene glycol, acetic acid, acetaldehyde, ethanol, propylene glycol, or isopropanol.

In particular, the electrochemical reduction of carbon dioxide to a carboxylate can be carried out with an electrochemical cell that has an anode compartment and a cathode compartment. Liquid is introduced to the anode compartment and carbon dioxide is introduced to the cathode compartment. The cathode compartment also contains a solution of electrolyte and a homogenous heterocyclic amine catalyst, wherein each bond of the homogenous heterocyclic amine catalyst is selected from the group consisting of: a carbon-carbon bond, a carbon-hydrogen bond, a carbon-nitrogen bond, a carbon-oxygen bond, a carbon- sulfur bond, a nitrogen-hydrogen bond, a nitrogen-nitrogen bond, a nitrogen- oxygen bond, and an oxygen-hydrogen bond. An electrical potential sufficient to reduce the carbon dioxide to a carboxylate is applied between the anode and the cathode in the respective compartment

In certain preferred embodiments, the reduction of the carbon dioxide to produce carboxylic acid intermediates, carboxylic acids, and glycols may be preferably achieved in a divided electrochemical or photoelectrochemical cell having at least two compartments. One compartment contains an anode suitable to oxidize water, and another compartment contains a working cathode electrode and a homogenous heterocyclic amine catalyst. The compartments may be separated by a porous glass frit, microporous separator, ion exchange membrane, or other ion conducting bridge. Both compartments generally contain an aqueous solution of an electrolyte. Carbon dioxide gas may be continuously bubbled through the cathodic electrolyte solution to preferably saturate the solution or the solution may be pre- saturated with carbon dioxide. As used herein, the term "glycol" or its grammatical equivalents will refer to compounds containing two alcohol functional groups, two alcohol functional groups and a carbonyl functionality, or any combination thereof. As used herein, the term "carbonyl functionality" will refer to an aldehyde functionality or a ketone functionality.

Referring to FIG. 1, a block diagram of a system 100 is shown, which may be utilized for electrochemical production of carboxylic acid intermediates, carboxylic acids, and glycols from carbon dioxide and water (and hydrogen for glycol production). System 100 generally comprises a cell 102, a liquid source 104 (preferably a water source, but may include an organic solvent source), an energy source 106, a gas source 108 (preferably a carbon dioxide source), a product extractor 110 and an oxygen extractor 112. A product or product mixture may be output from the product extractor 110 after extraction. An output gas containing oxygen may be output from the oxygen extractor 112 after extraction.

Cell 102 may be implemented as a divided electrochemical cell and/or a divided photochemical cell. In particular implementations, the cell 102 is operational to reduce carbon dioxide to carboxylic acid intermediates (including salts such as formate, glycolate, glyoxylate, oxalate, and lactate), carboxylic acids, and glycols. The reduction generally takes place by introducing (e.g., bubbling) carbon dioxide into an electrolyte solution in the cell 102. A cathode 120 in the cell 102 may reduce the carbon dioxide into a carboxylic acid or a carboxylic acid intermediate. The production of a carboxylic acid or carboxylic acid intermediate may be dependent on the pH of the electrolyte solution, with lower pH ranges favoring carboxylic acid production. The pH of the cathode compartment may be adjusted to favor production of one of a carboxylic acid or carboxylic acid intermediate over production of the other, such as by introducing an acid (e.g., HC1 or H2S04) to the cathode compartment. Hydrogen may be introduced to the carboxylic acid or carboxylic acid intermediate to produce a glycol or a carboxylic acid, respectively. The hydrogen may be derived from natural gas or water.

The cell 102 generally comprises two or more compartments (or chambers) 114 a- 114 b, a separator (or membrane) 116, an anode 118, and a cathode 120. The anode 118 may be disposed in a given compartment (e.g., 114 a). The cathode 120 may be disposed in another compartment (e.g., 114 b) on an opposite side of the separator 116 as the anode 118. In particular implementations, the cathode 120 includes materials suitable for the reduction of carbon dioxide including cadmium, a cadmium alloy, cobalt, a cobalt alloy, nickel, a nickel alloy, chromium, a chromium alloy, indium, an indium alloy, iron, an iron alloy, copper, a copper alloy, lead, a lead alloy, palladium, a palladium alloy, platinum, a platinum alloy, molybdenum, a molybdenum alloy, tungsten, a tungsten alloy, niobium, a niobium alloy, silver, a silver alloy, tin, a tin alloy, rhodium, a rhodium alloy, ruthenium, a ruthenium alloy, carbon, and mixtures thereof. An electrolyte solution 122 (e.g., anolyte or catholyte 122) may fill both compartments 114a- 114b. The aqueous solution 122 preferably includes water as a solvent and water soluble salts for providing various cations and anions in solution, however an organic solvent may also be utilized. In certain implementations, the organic solvent is present in an aqueous solution, whereas in other implementations the organic solvent is present in a non-aqueous solution. The catholyte 122 may include sodium and/or potassium cations or a quaternary amine (preferably tetramethyl ammonium or tetraethyl ammonium). The catholyte 122 may also include divalent cations (e.g., Ca2+, Mg2+, Zn2+) or a divalent cation may be added to the catholyte solution.

A homogenous heterocyclic catalyst 124 is preferably added to the compartment 114b containing the cathode 120. The homogenous heterocyclic catalyst 124 may include, for example, one or more of 4-hydroxy pyridine, adenine, a heterocyclic amine containing sulfur, a heterocyclic amine containing oxygen, an azole, a benzimidazole, a bipyridine, furan, an imidazole, an imidazole related species with at least one five-member ring, an indole, a lutidine, methylimidazole, an oxazole, phenanthroline, pterin, pteridine, a pyridine, a pyridine related species with at least one six-member ring, pyrrole, quinoline, or a thiazole, and mixtures thereof. The homogenous heterocyclic catalyst 124 is preferably present in the compartment 114b at a concentration of between about 0.001M and about 1M, and more preferably between about 0.01M and 0.5M.

The pH of the compartment 114 b is preferably between about 1 and 8. A pH range of between about 1 to about 4 is preferable for production of carboxylic acids from carbon dioxide. A pH range of between about 4 to about 8 is preferable for production of carboxylic acid intermediates from carbon dioxide.

The liquid source 104 preferably includes a water source, such that the liquid source 104 may provide pure water to the cell 102. The liquid source 104 may provide other fluids to the cell 102, including an organic solvent, such as methanol, acetonitrile, and dimethylfuran. The liquid source 104 may also provide a mixture of an organic solvent and water to the cell 102.

The energy source 106 may include a variable voltage source. The energy source 106 may be operational to generate an electrical potential between the anode 118 and the cathode 120. The electrical potential may be a DC voltage. In preferred embodiments, the applied electrical potential is generally between about -1.5V vs. SCE and about -4V vs. SCE, preferably from about -1.5V vs. SCE to about -3V vs. SCE, and more preferably from about -1.5 V vs. SCE to about -2.5V vs. SCE.

The gas source 108 preferably includes a carbon dioxide source, such that the gas source 108 may provide carbon dioxide to the cell 102. In some embodiments, the carbon dioxide is bubbled directly into the compartment 114 b containing the cathode 120. For instance, the compartment 114 b may include a carbon dioxide input, such as a port 126 a configured to be coupled between the carbon dioxide source and the cathode 120.

The product extractor 110 may include an organic product and/or inorganic product extractor. The product extractor 110 generally facilitates extraction of one or more products (e.g., carboxylic acid, and/or carboxylic acid intermediate) from the electrolyte 122. The extraction may occur via one or more of a solid sorbent, carbon dioxide-assisted solid sorbent, liquid-liquid extraction, nanofiltration, and electrodialysis. The extracted products may be presented through a port 126 b of the system 100 for subsequent storage, consumption, and/or processing by other devices and/or processes. For instance, in particular implementations, the carboxylic acid or carboxylic acid intermediate is continuously removed from the cell 102, where cell 102 operates on a continuous basis, such as through a continuous flow-single pass reactor where fresh catholyte and carbon dioxide is fed continuously as the input, and where the output from the reactor is continuously removed. In other preferred implementations, the carboxylic acid or carboxylic acid intermediate is continuously removed from the catholyte 122 via one or more of adsorbing with a solid sorbent, liquid-liquid extraction, and electrodialysis.

The separated carboxylic acid or carboxylic acid intermediate may be placed in contact with a hydrogen stream to produce a glycol or carboxylic acid, respectively. For instance, as shown in FIG. IB, the system 100 may include a secondary reactor 132 into which the separated carboxylic acid or carboxylic acid intermediate from the product extractor 110 and hydrogen stream from a hydrogen source 134 are introduced. The secondary reactor 132 generally permits interaction between the separated carboxylic acid or carboxylic acid intermediate from the product extractor 110 and the hydrogen to produce a glycol or carboxylic acid, respectively. The secondary reactor 132 may include reactor conditions that differ from ambient conditions. In particular implementations, the secondary reactor 132 preferably includes a temperature range and a pressure range that is higher than that of ambient conditions. For instance, a preferred temperature range of the secondary reactor 132 is between about 50° C. and about 500° C, and a preferred pressure range of the secondary reactor 132 is between about 5 atm and 1000 atm. The secondary reactor may include a solvent and a catalyst to facilitate the reaction between the separated carboxylic acid or carboxylic acid intermediate from the product extractor 110 and the hydrogen stream from the hydrogen source 134. Preferred catalysts include Rh, Ru02, Ru, Pt, Pd, Re, Cu, Ni, Co, Cu— Ni, and binary metals and/or metal oxides thereof. The catalyst may be a supported catalyst, where the support may include Ti, Ti02, or C. Preferred solvents include aqueous and non-aqueous solvents, such as water, ether, and tetrahydrofuran.

The oxygen extractor 112 of FIG. 1A is generally operational to extract oxygen (e.g., 02) byproducts created by the reduction of the carbon dioxide and/or the oxidation of water. In preferred embodiments, the oxygen extractor 112 is a disengager/flash tank. The extracted oxygen may be presented through a port 128 of the system 100 for subsequent storage and/or consumption by other devices and/or processes. Chlorine and/or oxidatively evolved chemicals may also be byproducts in some configurations, such as in an embodiment of processes other than oxygen evolution occurring at the anode 118. Such processes may include chlorine evolution, oxidation of organics to other saleable products, waste water cleanup, and corrosion of a sacrificial anode. Any other excess gases (e.g., hydrogen) created by the reduction of the carbon dioxide and water may be vented from the cell 102 via a port 130.

Referring to FIG. 2, a flow diagram of a preferred method 200 for electrochemical conversion of carbon dioxide is shown. The method (or process) 200 generally comprises a step (or block) 202, a step (or block) 204, a step (or block) 206, and a step (or block) 208. The method 200 may be implemented using the system 100.

In the step 202, a liquid may be introduced to a first compartment of an electrochemical cell. The first compartment may include an anode. Introducing carbon dioxide to a second compartment of the electrochemical cell may be performed in the step 204. The second compartment may include a solution of an electrolyte, a cathode, and a homogenous heterocyclic amine catalyst. The descriptions for these components have been described above and will not be repeated here. In the step 206, an electric potential may be applied between the anode and the cathode in the electrochemical cell sufficient for the cathode to reduce the carbon dioxide to a carboxylic acid intermediate. The production of the carboxylic acid intermediate is preferably controlled by selection of particular cathode materials, catalysts, pH ranges, and electrolytes, such as disclosed in U.S. Application Ser. No. 12/846,221, the disclosure of which is incorporated by reference. Contacting the carboxylic acid intermediate with hydrogen to produce a reaction product may be performed in the step 208. The secondary reactor 132 may permit interaction/contact between the carboxylic acid intermediate and the hydrogen, where the conditions of the secondary reactor 132 may provide for production of particular reaction products.

Referring to FIG. 3, a flow diagram of another preferred method 300 for electrochemical conversion of carbon dioxide is shown. The method (or process) 300 generally comprises a step (or block) 302, a step (or block) 304, a step (or block) 306, a step (or block) 308, a step (or block) 310, and a step (or block) 312. The method 300 may be implemented using the system 100.

In the step 302, a liquid may be introduced to a first compartment of an electrochemical cell. The first compartment may include an anode. Introducing carbon dioxide to a second compartment of the electrochemical cell may be performed in the step 304. The second compartment may include a solution of an electrolyte, a cathode, and a homogenous heterocyclic amine catalyst. In the step 306, an electric potential may be applied between the anode and the cathode in the electrochemical cell sufficient for the cathode to reduce the carbon dioxide to at least a carboxylate. Acidifying the carboxylate to convert the carboxylate into a carboxylic acid may be performed in the step 308. The acidifying step may include introduction of an acid from a make-up acid source. In the step 310, the carboxylic acid may be extracted. Contacting the carboxylic acid with hydrogen to form a reaction product may be performed in the step 312. In preferred implementations, the reaction product includes one or more of formaldehyde, methanol, glycolic acid, glyoxal, glyoxylic aid, glycolaldehyde, ethylene glycol, acetic acid, acetaldehyde, ethanol, propylene glycol, or isopropanol. In yet another embodiment, carbon dioxide may be electrochemically reduced to formic acid, which can be contacted with hydrogen to form a reaction product as described above, which includes at least one of formaldehyde, methanol, glycolic acid, glyoxal, glyoxylic acid, glycolaldehyde, ethylene glycol, acetic acid, acetaldehyde, ethanol, propylene glycol, or isopropanol. One illustrative manner to electrochemically reduce carbon dioxide to formic acid is described in US4160816, the disclosure of which is incorporated herein by reference.

In particular, the electrochemical reduction of carbon dioxide to formic acid or formate ion can take place in both basic and acidic solutions.

In basic solution, the overall reaction proceeds as follows:

C02 + H20 (2e-j HC02- + OH-

The formate ion HC02- can be converted into formic acid by rendering the basic solution acidic.

In acidic solution, the overall reaction proceeds as follows:

C02 + 2H+ (26--) HCOOH

Although different mechanisms for the electrochemical reactions have been hypothesized by various workers, the overall import of the work performed with respect to reduction of carbon dioxide to formic acid in solution is that at neutral or basic pH, the formic acid remains in solution as the formate ion.

The ratio of acid or ion form in solution depends upon the pH. At a pH above the equilibrium, i.e., about pH 3.75, the ion form is in higher concentrations than the acid form. Below the equilibrium pH, formic acid is in higher concentrations than formate ions.

Carbon dioxide gas may be diffused over the cathode. In some embodiments, at least about 1.50 volts is applied at the cathode for the reduction of the carbon dioxide to formic acid at the interface of the carbon dioxide-cathode- electrolyte solution interface in the cell.

In some embodiments, the anode of the cell may be of any suitable material which is inert with respect to the electrolyte for example, graphite, titanium dioxide, etc. The cathode can be of a suitable material. The pH of the electrolyte solution in the cell may be adjusted to increase or favor the production of formic acid and inhibit the formation of hydrogen. The efficiency of the formation of formic acid tends to decrease with increasing acidity of the solution because of the competition at the cathode for the production of hydrogen. Buffers, such as sodium bicarbonate, may be used. Generally, the temperature may vary from about 5° C to about 100° C and preferably 20° C to 50° C.

The electrochemical reduction of carbon dioxide to formic acid may also be carried out via the methods and processes disclosed in US8562811, the disclosure of which is incorporated herein by reference. In a particular embodiment, there is provided a method for electrochemical production of at least formic acid, comprising: (A) introducing water to a first compartment of an electrochemical cell, the first compartment including an anode; (B) introducing carbon dioxide to a second compartment of the electrochemical cell, the second compartment including a solution of an electrolyte and a cathode, the cathode is selected from the group consisting of indium, lead, tin, cadmium, and bismuth, the electrolyte in the second compartment having a pH of between approximately 4 and 7; (C) applying an electrical potential between the anode and the cathode in the electrochemical cell sufficient to reduce the carbon dioxide to formic acid; and (D) maintaining a concentration of formic acid in the second compartment at or below approximately 500 ppm. The solution of electrolyte can includes potassium sulfate, potassium chloride, sodium chloride, sodium sulfate, lithium sulfate, sodium perchlorate, lithium chloride, or any combination thereof. The concentration of formic acid in the second compartment is maintained at or below approximately 500 ppm by removing formic acid from the second compartment. The second compartment can further include divalent ions, such as magnesium ions, calcium ions, strontium ions, barium ions, or any combination thereof. Preferably, the pH of the electrolyte in the second compartment is maintained to between approximately 4.3 and approximately 5.5. The second compartment can further include a heterocyclic aromatic amine selected from the group consisting of 4-hydroxy pyridine, adenine, a heterocyclic amine containing sulfur, a heterocyclic amine containing oxygen, an azole, benzimidazole, a bipyridine, furan, an imidazole, an imidazole related species with at least one five-member ring, an indole, methylimidazole, an oxazole, phenanthroline, pterin, pteridine, a pyridine, a pyridine related species with at least one six-member ring, pyrrole, quinoline, a thiazole, and any combination thereof. It is understood the electrochemical reduction can further produce methanol, acetone, or isopropanol in the electrolyte solution.

The formic acid generated via the electrochemical reduction of carbon dioxide as described can be contacted with hydrogen via a hydrogenation reaction as described above, particularly with respect to secondary reactor 132 to generate a reaction product comprising a glycol or carboxylic acid. Accordingly, as described herein, embodiments herein provide electrochemical reduction of carbon dioxide through the use of electricity generated by solar energy to generate various reduced compounds, which can be further contacted with hydrogen to produce a reaction product containing various compounds. The product reactions of methanol and glycol (i.e., diols such as ethylene glycol and propylene glycol), whether directly obtained from the electrochemical reduction of carbon dioxide or subsequent processing of the reduced compounds can be provided for additional condensation reactions to produce higher molecular weight hydrocarbons that can be used in a fuels product.

As provided thus far, electrochemical reduction of carbon dioxide and subsequent processing of the reduced compounds can produce glycols, which are a subset or a species of polyols. As used herein, the term "glycol" or its grammatical equivalents will refer to compounds containing two alcohol functional groups, two alcohol functional groups and a carbonyl functionality, or any combination thereof. As used herein, the term "carbonyl functionality" will refer to an aldehyde functionality or a ketone functionality. As used herein, the term "polyol" or its grammatical equivalents will refer to compounds containing two or more alcohol functional groups, two or more alcohol functional groups and a carbonyl functionality, or any combination thereof.

Additionally or alternatively to methods and systems described above, cellulose or sugars can be electrolyzed to form polyols, including glycols as well, where the polyols can be similarly processed to produce a drop-in fuels component as described with the optional step of contact with acidic silica alumina catalyst and a condensation reaction. Any type of suitable electrical energy can be used to power the electrolysis, and it can preferably come from at least one of nuclear, hydroelectric, wind, geothermal, and solar power. Suitable methods for electrolyzing a biomass substrate to form sugars and subsequent electrolysis to convert sugars to form polyols are known in the art. The conversion from cellulose to polyols can be conducted in two electrolysis cells to generate reducible sugars from cellulose in a first cell and reduction of the reducible sugars to polyols in a second cell. Additionally or alternatively, a single cell may be used to effect the conversion of cellulose to polyols since hydrolysis of cellulose to glucose by a hydroxyl radical (*OH) takes place at an anode and glucose hydrogenation (e.g., reduction of sugars) to a polyol occurs at a cathode in an electrolysis cell. In a one- cell electrosynthesis of polyols from a biomass substrate can be achieved by transferring the glucose generated from anode can be to the cathode inlet for further hydrogenation to a polyol, such as sorbitol.

Electrochemical Hydrolysis

In general, electrochemical hydrolysis is known in the art for use to degrade a biomass substrate (such as lignocellulosic material) into its components and derivatives of the components. As used herein, "degradation" and grammatical equivalents refer to the separation of lignocellulose into its component parts of lignin, cellulose and hemicellulose as well as the further conversion of those parts to useful chemicals and materials. In particular, acid (H+) and (OH*) can be electrochemically generated at an anode of an electrochemical cell, which can provide for electrochemical hydrolysis of biomass.

For instance, a suitable electrochemical hydrolysis of a biomass substrate is disclosed in US Patent No. 4341609, the disclosure of which is incorporated herein by reference. The biomass substrate can by any lignocellulosic biomass material which is capable of being degraded in an electrolytic cell. Suitable lignocellulosic material may include, for example, forestry residues, agricultural residues, herbaceous material, municipal solid wastes, waste and recycled paper, pulp and paper mill residues, and any combination thereof. Thus, in some embodiments, a suitable cellulosic biomass may include, for example, corn stover, straw, bagasse, miscanthus, sorghum residue, switch grass, bamboo, water hyacinth, hardwood, hardwood chips, hardwood pulp, softwood, softwood chips, softwood pulp, duckweed and any combination thereof. Leaves, roots, seeds, stalks, husks, and the like may be used as a source of the lignocellulosic biomass. Common sources of lignocellulosic biomass may include, for example, agricultural wastes (e.g., corn stalks, straw, seed hulls, sugarcane leavings, nut shells, and the like), wood materials (e.g., wood or bark, sawdust, timber slash, mill scrap, and the like), municipal waste (e.g., waste paper, yard clippings or debris, and the like), and energy crops (e.g., poplars, willows, switch grass, alfalfa, prairie bluestream, corn, soybeans, and the like). Additionally or alternatively, components of lignocellulose (e.g. pure cellulose, hemicellulose, or lignin) can serve as the biomass substrate.

The electrochemical hydrolysis is conducted in an electrochemical cell. Any size or shape of container which is designed for or capable of being adapted for use as an electrochemical cell can be used. Preferably, the cell is designed to provide easy handling of the biomass material and the electrolyte solution, and is optionally provided with a means for stirring or agitating the contents of the cell during the process.

A porous barrier is provided to separate the cell into two sections. This barrier, typically positioned latitudinally between the sections, prevents the electrodes from making a short-circuit yet provides an ionic conducting path from one side of the cell to the other. It also prevents hydrogen and oxygen gases from mixing together inside the cell. Preferably, the barrier is selected from a material which is resistant to corrosion by the electrolyte in the presence of hydrogen or oxygen. A preferred barrier for use in this invention is sinterglass.

At least one electrode is provided for each section of the cell. Almost any electronic conductor having a suitable catalytic service for the discharge of ions can be used. An electrode will advantageously have a large surface area to maximize the interface between the catalyst and the electrolyte solution. The specific size and shape will vary according to the design of the overall cell, although an electrode of 40 sq cm has been found to be suitable for a cell section having a volume capacity of about 70 ml of electrolyte. The electrode preferably has a means for detaching gas bubbles as they form in order to separate them from the electrolyte solution, but this is not essential. As is known in the art of electrolysis, the choice of material for the electrode also depends upon the choice of the electrolyte solution, because strong electrolyte solutions will corrode certain materials. Carbon and highly conductive metals such as platinum are especially suitable for use in this invention and are preferred.

Any electrolyte which shows high ionic conductivity and has no detrimental effects on the process or the desired reaction product can be used. During the process, water is decomposed from the aqueous electrolyte solution into hydrogen and oxygen gas. The electrolyte should therefore not be volatile enough to be removed with the evolving gas and must not be chemically decomposed itself by the process. If the process is conducted for an extended period of time, additional water can be added to the system to replace water lost by decomposition. Aqueous solutions of sulfuric acid and sodium hydroxide are preferred electrolytes. Other suitable electrolytes include ethylenediamine and ethylenediamine tetroacetic acid (EDTA).

The electrochemical hydrolysis process can be conducted at any temperature between the freezing and boiling points of the electrolyte solution. Although the process proceeds more rapidly at higher temperatures, ambient or slightly higher temperatures are preferred for reasons of economy. Process temperatures between 20° and 35° C. are especially preferred.

Any suitable direct current power source may be connected to the electrolytic cell at the electrodes. In one embodiment, the energy source is selected from the group consisting of nuclear, hydroelectric, wind, geothermal, and solar power. As is the convention in electrolysis, the anode is the positive terminal of the cell. As is well known in the art, the potential needed to pass a current between the electrodes will vary with the distance between the electrodes and the conductivity of the electrolyte. The potential between the electrodes of smaller cells can vary from 5 to 50, preferably 10 to 30 and most preferably 10 to 15 volts. The current can range from 0.5 to 5, preferably 0.5 to 3 and most preferably about 1.5 amperes.

The time required for completion of the process will depend upon several factors including temperature, amount of substrate and electrolyte and electricity. At the conditions described in the examples, significant degradation occurred when the reaction had proceeded for 4-10 days. The effects of this degradation can be observed during the course of the electrochemical treatment by the change in appearance from a dark brown to a fluffy substrate. The process can be continued until extensive separation and degradation of the lignocellulose has occurred. Alternatively, the process can be operated for a shorter time as a pretreatment of lignocellulose which is then further treated by other known methods. Electrolytic Reduction of Sugars

As described above, electrolysis of a biomass substrate, such as cellulose or cellobiose, can produce reducible sugars, which include mono- and polysaccharides such as glucose, fructose, mannose, lactose, galactose, sucrose, and others. The reduction or hydrogenation of reducible sugars by the electrolytic process is a known and commercially practiced operation. Broadly the process involves the use of an electrolytic diaphragm cell providing separated anode and cathode compartments. The anolyte is a solution of an electrolyte, preferably sulfuric acid, in water. The catholyte is a solution of the sugar to be reduced together with a suitable electrolyte in water. In the catholyte, the electrolyte is preferably an alkali metal compound, like sodium sulfate to which is frequently added an alkali hydroxide. In addition to the electrolyte, an alkali or acid can be added to the catholyte at the start of the reduction. The amount of alkali or acid used is a factor in determining the nature of the product to be produced. The catholyte tends to become alkaline in the course of a reduction, and, if desired, no alkali or acid need be added at the start of the reduction. Some of the polysaccharides such as lactose can be inverted and reduced in one operation under acid catholyte condition.

The anode in the process is an electrically conductive material resistant to the corrosive action of the anolyte. In commercial practice, the cathode is preferably a rigid plate of lead or zinc. The cathode may also be made of any rigid material and covered with a layer of lead or zinc. Lead cathodes are amalgamated before use. Zinc cathodes are used either amalgamated or unamalgamated. When the anode and cathode are connected to a source of direct current nascent hydrogen is formed at the cathode and sugar in the catholyte solution is thereby reduced to one or more polyhydric alcohols.

By means of this electrolytic process a series of polyhydric alcohols can be made from reducible sugars. Conditions can be selected to produce the polyhydric alcohol which directly corresponds to the sugar, or to produce mixtures of polyhydric alcohols (i.e., polyols) some of which do not correspond directly to the sugar. Thus, from glucose can be made sorbitol, which is the corresponding hexitol, or a mixture of mannitol and sorbitol can be made, or the product can be composed of mannitol, sorbitol and other polyhydric alcohols such as hexane pentols. The last two types of products are produced when the catholyte solution is maintained at a relatively high alkalinity while the first type is made at very low alkalinity or with the catholyte in a neutral or acid condition. This process is more completely described in the U.S. Patent Nos. 1990582, 2289189, 2289190, 2300218 and 2303210, the disclosures of each is incorporated herein by reference.

The overall process is illustrated in FIG. 4, which illustrates embodiments of preferred method 400 for using solar energy to convert carbon dioxide to a higher molecular weight hydrocarbon. Method 400 generally comprises a step (or block) 402, a step (or block) 404, a step (or block) 406, a step (or block) 408, and a step (or block) 410.

In the step 402, solar energy is converted to electricity using methods known to one of ordinary skill in the art. In step 404, the electricity converted from solar energy is applied to an electrochemical cell as described above to reduce carbon dioxide to generate reduced compounds. It is understood that energy from any source can be used in the methods and systems described herein. In step 404, suitable methods to electrochemically reduce carbon dioxide may be used. Illustrative methods and systems are described above. In one embodiment, the reduced compounds generated in step 404 can comprise methanol, which can then be provided directly to a condensation reaction, as further described below. In step 406, optionally, the reduced compounds may comprise a carboxylic acid or a carboxylic acid intermediate (carboxylate), which can be processed to generate a glycol using systems and methods known to one of ordinary skill. For instance, the carboxylate can be acidified to generate a carboxylic acid and/or contacting the carboxylic acid, including formic acid, with hydrogen to generate a reaction product comprising formaldehyde, methanol, glycolic acid, glyoxal, glyoxylic aid, glycolaldehyde, ethylene glycol, acetic acid, acetaldehyde, ethanol, propylene glycol, isopropanol, or any combination thereof. Additionally or alternatively, cellulose can be electrolyzed to sugars, which can then be reduced to a polyol. In step 408, the reaction product from step 406 comprising a polyol, such as glycols, can be optionally provided to a diol conversion zone where glycols are contacted with an acidic silica alumina catalyst under certain reaction conditions to produce a mono-oxygenated stream prior to condensation reaction. Providing the mono- oxygenated stream from step 408 to the condensation reaction of step 410 can allow for extending the life of catalysts used in subsequent processing steps and producing components valuable as liquid fuels. In step 410, the reduced compounds comprising methanol from step 404, the reaction product comprising methanol and/or glycols from step 406, and/or the mono-oxygenated stream from step 408 can be provided to a condensation reaction to generate a higher molecular weight hydrocarbon as further described below.

In optional step 408, the reaction product from step 406 comprising glycols can be optionally provided to a diol conversion zone where it is contacted with an acidic amorphous silica alumina catalyst at a temperature in the range from 300°C to 400°C, preferably 325°C to 375°C, thereby producing mono-oxygenated stream as described in commonly owned U. S. Patent Application Nos. 62/186941, 62/186902, 62/186919, 62/186960, all filed on June 30, 2015, each of which are incorporated herein by reference in its entirety. In particular, the mono-oxygenated stream contains water and monooxygenates having a boiling point of at least 40°C. The temperature and pressure is at a range that optimizes diol conversion while minimizing coke formation (by oligomerization or condensation reactions). The pressure range may be from ambient pressure (atmospheric) to a higher partial pressure, for example, total pressure of up to about 200 psi. The reaction typically converts at least 25%, preferably at least 50%, most preferably at least 75% of diols (glycols) initially present. Typically, the weight hourly space velocity is in the range of 0.2 to 5 for the mono-oxygenate formation step.

The acidic amorphous silica-alumina catalyst is a solid catalyst that may be prepared in a number of ways which are known in the art. For example, by precipitating alumina in a silica slurry, followed by firing. Some other examples include precipitation of hydrous alumina onto amorphous silica hydrogel, reacting a silica sol with an alumina sol, coprecipitation from sodium silicate / aluminium salt solution. The sulfate and the sodium, which may be introduced with the alumina precursors and sulfuric acid, may be removed by washing. The resulting silica alumina material can be shaped in various shapes, for example, by extruding, oil drop process, or pressing. To produce the acidic amorphous silica-alumina catalyst, the material is dried and calcined. The BET surface area of the catalyst is typically greater than 200 m2/g, preferably in the range of 300 m2/g to 500 m2/g. The total pore volume is typically in the range of 0.7 to 1.0 cc/g measured using water method. Although described herein as amorphous, the silica alumina materials useful in embodiments described herein may contain a minor amount of crystalline alumina and/or aluminosilicate, depending on the source of the alumina material used to prepare the precipitated alumina-silica precursor, the amount of the alumina in the alumina-silica, as well as the calcination temperature. The ratio of silica to alumina may vary between 1:99 to 99:1, preferably 15:85 to 96:4. In some embodiment, 15:85 to 65:35, preferably 15:85 to 30:70 for low silica content solid amorphous silica-alumina catalyst, preferably 35:65 to 55:45 for higher silica solid amorphous silica-alumina catalyst. In another embodiment, milder acidity amorphous silica to alumina catalyst, the ratio of silica to alumina may vary between 45:55 to 96:4, more preferably 45:55 to 90:10. Solid acid amorphous silica-alumina catalyst is available commercially, for example, from Criterion Catalyst Co., such as X-600 catalyst series, X-503 catalyst, X-801 catalyst or from CRI Catalyst Company such as KL-7122 catalyst. The monooxygenated stream can be optionally be condensed (in this instance referred to liquid condensation without chemical transformation) in a cooling zone, to liquid producing an aqueous phase and an organic phase. The mono-oxygenated stream optionally can be phase separated into an aqueous phase and an organic phase upon condensation, thus allowing the aqueous phase containing water and a residual amount of unconverted mono-oxygenated compounds and diols of carbon number less than four, to be readily removed from the organic phase enriched in mono-oxygenated organic compounds greater than carbon number four, and phenolic compounds. By optionally separating the water before contact with the condensation catalyst, catalyst life can be further extended.

In step 410, at least a portion of the plurality of oxygenated hydrocarbon and/or organic phase containing the monooxygenates or the monooxygenate- containing stream from step 408 is provided to a condensation reaction. As used herein, the term "condensation reaction" will refer to a chemical transformation in which two or more molecules are coupled with one another to form a carbon- carbon bond in a higher molecular weight compound, usually accompanied by the loss of a small molecule such as water or an alcohol. The term "condensation catalyst" will refer to a catalyst that facilitates, causes, or accelerates such chemical transformation. In the condensation reaction, at least a portion of the plurality of oxygenated hydrocarbon and/or organic phase containing the monooxygenates or the monooxygenate-containing stream is contacted with a solid acid condensation catalyst separate from the diol conversion zone at a temperature in the range from 275°C to about 425 °C producing a higher molecular weight hydrocarbons stream in a condensation reaction zone. In various embodiments, the higher molecular weight compound or hydrocarbon produced by the condensation reaction may comprise >C4 hydrocarbons. In some or other embodiments, the higher molecular weight compound produced by the condensation reaction may comprise >C6 hydrocarbons. In some embodiments, the higher molecular weight compound produced by the condensation reaction may comprise C4 - C30 hydrocarbons. In some embodiments, the higher molecular weight compound produced by the condensation reaction may comprise C6 - C30 hydrocarbons. In still other embodiments, the higher molecular weight compound produced by the condensation reaction may comprise C4 - C24 hydrocarbons, or C6 - C24 hydrocarbons, or C4 - C18 hydrocarbons, or C6 - C18 hydrocarbons, or C4 - C12 hydrocarbons, or C6 - C12 hydrocarbons. As used herein, the term "hydrocarbons" refers to compounds containing both carbon and hydrogen without reference to other elements that may be present. Thus, heteroatom-substituted compounds are also described herein by the term "hydrocarbons."

The particular composition of the higher molecular weight compound produced by the condensation reaction may vary depending on the catalyst(s) and temperatures used for the condensation reaction, as well as other parameters such as pressure. Suitable condensation catalysts include, for example, acid condensation catalysts described in US20140275515 which disclosure is hereby incorporated by reference.

The condensation products comprising higher molecular weight hydrocarbons may be aromatics-rich hydrocarbon stream when a shape selective condensation catalyst, such as zeolitic catalyst, particularly ZSM-5 catalyst is used in the condensation reaction. To produce aromatics-rich hydrocarbon stream, the acidic ZSM-5 catalyst is contacted at a temperature in the range from 325 °C to about 425°C, preferably 350°C to 400°C, in the condensation reaction zone. The temperature and pressure are at a range that optimizes condensation reaction while minimizing coke formation. The pressure range may be from ambient pressure (atmospheric) to slight partial pressure, for example, total pressure of up to about 200psi. The aromatics rich hydrocarbon stream can optionally be washed with aqueous base such as sodium hydroxide, potassium hydroxide to remove residual acids and phenolics (washing zone) to produce biofuel useful as gasoline. These aqueous bases typically have a pH of at least 9. The aromatics -rich higher hydrocarbons stream may have at least 50wt% of aromatics containing hydrocarbon based on the aromatics-rich hydrocarbons stream. The entire organic phase can also be sent to the condensation step. The yield may be greater than 40% of carbons based on biomass carbons due to the increase catalyst uptime (amount of monooxygenated stream passed over the condensation catalyst). Aromatics as defined herein can be quantified by GC-MS analysis and includes any aromatic containing hydrocarbon that contains aromatic rings that are not oxygenated, such as mesytilene, based on molecular content.

The condensation product may be low aromatics, paraffinics-containing stream (aliphatic -rich higher hydrocarbons) when other than shape selective condensation catalyst described above is used in the condensation reaction. The low aromatics, paraffinic-containing stream may be further treated in a hydrotreating step (hydrotreating zone) to produce biofuel useful as diesel. This step can be any conventional hydrotreating process. This includes fixed or ebulated bed operations at conventional operating conditions such as temperatures in the range of 250° C to 450° C, preferably 300°C to 380° C. Pressures are also conventional such as 20-70 bar of hydrogen. Catalysts used in the hydrotreating step are preferably those employed conventionally, such as mixed cobalt and/or nickel and molybdenum sulfides supported on alumina and mixed nickel and tungsten sulfides supported on alumina or silica.

At least a portion of the organic phase containing the monooxygenates and/or plurality of oxygenated hydrocarbon may be contacted with a solid acid condensation catalyst under conditions effective to produce low aromatics, paraffinics-containing stream in the acid condensation reaction to produce an aliphatics and the monooxygenate-containing stream may be contacted with a ZSM-5 catalyst under conditions effective to produce aromatics-rich hydrocarbons stream in acid condensation zone. The aromatics-rich hydrocarbons stream may be base washed.

The condensation reaction mediated by the condensation catalyst may be carried out in any reactor of suitable design, including continuous-flow, batch, semi-batch or multi-system reactors, without limitation as to design, size, geometry, flow rates, and the like. The reactor system may also use a fluidized catalytic bed system, a swing bed system, fixed bed system, a moving bed system, or a combination of the above. In some embodiments, bi-phasic (e.g., liquid-liquid) and tri-phasic (e.g., liquid-liquid-solid) reactors may be used to carry out the condensation reaction.

Accordingly, embodiments of the present disclosure allow for production of higher molecular weight hydrocarbons that have similar properties as those produced from fossil fuels and can be readily blended with existing fuels products from a renewable energy source that is not biomass, thereby avoiding the challenges associated with producing biofuels from biomass. In addition, embodiments of the present disclosure also allow for reduction of the greenhouse gas carbon dioxide.

To facilitate a better understanding of the present invention, the following examples of preferred embodiments are given. In no way should the following examples be read to limit, or to define, the scope of the invention.

Examples

Comparative Example A

Ni was impregnated on ZSM-5 (CBV2314 having SAR of 23 from Zeolyst International). 50g of ZSM-5 1/8 inch extrudate was impregnated with Νί(Ν03)2·6Η20 (2.48g) dissolved in deionized water (13.76g) by insipient wetness. After all the liquid had been adsorbed, the extrudate was dried for lhr at 125°C, then calcined for 3 hrs at 400°C.

A model feed mixture of glycol without contact with amorphous silica alumina in step 408 was prepared with PG/EG/water (wt% 45%/5%/50) and charged to a ½ OD continuous flow reactor containing 13.24g of the Ni impregnated ZSM-5 (condensation catalyst), 7 bar hydrogen flowing at 50cc/min. WHSV 1.22 total feed, 0.6 on organic basis. The condensation catalyst needed to be regenerated due to loss of activity from coking. Reaction ran for 1 day at which point, the condensation catalyst was making only traces of product. Coke burn restored activity, but activity was completely lost again after 2nd sample (1 day).

Example 1 : Condensation Reaction of a Mono-Oxygenated Stream

A model feed mixture representing a mono-oxygenated stream (i.e., a diol conversion product mixture after contact with amorphous silica alumina in step 408) was prepared with IPA/THF/acetone/acetic acid/1,3 PDO/water (wt.% 15/7/4/3/1/70) and charged to a ½ inch OD continuous flow reactor containing 13.4g Ni impregnated ZSM-5 (SAR23) (condensation catalyst) prepared as above, at 375°C, 7 bar hydrogen flowing at 50 cc/min. WHSV 1.0 total feed, 0.3 on organic basis. The catalyst needed to be regenerated due to loss of activity from coking. Coke burns were carried out once per week. Product from this reaction was 15% organic phase. As can be seen above, by feeding a lower diol content feed representing diol conversion-treated feed after contact with amorphous silica alumina compared to directly feeding diols to ZSM-5 condensation reaction in Comparative Example A, the activity between coke burns was extended from daily to once a week.

Example 2: Diol Conversion

A glycol containing feed was diluted 1/1 with DI water 7.5g of ASA X600 (amorphous silica alumina trilobe extrudate from Criterion Catalyst Co., LP, 55% alumina (A1203), 45% silica (Si02)) was charged to a 10 inch reactor and heated to 350 deg C under flowing nitrogen (50cc/min, 130 psig reactor pressure). Feed was introduced at 7.2 g/hr. 85g of liquid product was collected of which 7g was organic phase while the remainder comprised an aqueous phase.

GC/MS identification of ASA product organic phase components is provided in Table 1 below.

Table 1.

Example 3: Condensation

Both phases from Example 2 were recombined and a portion fed over 7.5g of ZSM-5 (CBV2314 Zeolite from Zeolyst International) (condensation catalyst) at a rate of 14g/hr. 65g of product was collected, 2.6g of organic phase and the remainder an aqueous phase.

A table of compiled GCMS data from the composition of the glycol feed in Example 2, the diol-converted/mono-oxygenates from Example 2, and the condensation product from Example 3 above is provided below. Other is C5-C6 higher oxygenates such as triols etc.

Table 2

As can be seen from the table above, diols were below detection limit after diol conversion reaction with ASA.

The GC of the glycol feed to Example 2 is shown in Fig. 5. The GC of the diol conversion product from Example 2 is shown in Fig. 6. The GC of the aromatization product from Example 3 is shown in Fig.7.

Example 4: Diol Conversion

A model feed of a glycol-containing mixture was prepared with PG/EG/butanediol/pentanediol/water feed (wt% 3.75/3.75/3.75/3.75/85), and charged to a 1/2 inch OD continuous flow reactor containing 7.6856g ASA X600 (amorphous silica alumina from Criterion Catalyst Co., LP, 55% alumina (A1203), 45% silica (Si02)) at 350°C and 7.6 barg with nitrogen flow at 50cc/min. WHSV 1.56g/g on total feed basis, (0.23 g/g on organic basis). The products from this reaction were condensed at ambient temperature and pressure. Product from this reaction was approx. 1% organic and 99% aqueous. The organic phase had no remaining detectable diols by GC-MS. The organic phase contained 33- 68wt% monooxygenates including cyclic ethers such as tetrahydro pyrane, methyl tetrahydrofuran and aldehydes such as pentanal and butanal, propanal and acetone and 3 wt% olefins and dienes, substituted aromatics and higher hydrocarbons in the range of C5 - C12.

Example 5: Condensation Reaction of products from Example 4

The organic phase from Example 4 was decanted from the aqueous phase and charged to a second ¼ inch OD flow reactor equipped with a 2mL injection port to allow small samples to be charged in plug flow. Reactor conditions were 0.5580g ASA X600 (amorphous silica alumina from Criterion Catalyst Co., LP,

55% alumina (A1203), 45% silica (Si02)), at 350°C, 52barg with 75ccmin of flowing N2. WHSV 3.2 g/g based on total flow (organic only). Product from this reaction was 14% organic layer, remainder aqueous. The organic product contained less than 21 percent monooxygenates and primarily higher hydrocarbons such as C10-C16. This product may be hydrotreated to produce a product useful as diesel fuel.

Gas Chromatograph of the condensation product compared with a commercial No. 2 standard diesel is provided in Fig. 8 and Fig. 9. For the gas chromatography , one microliter sample of the intermediate was injected into a GC insert held at 250°C, followed by Restek RTX-1701 (60m) and DB-5 (60 m( capillary GC columns in series (120 m total length, 0.32mm ID, 0.25μιη film thickness) for an Agilent/HP 6890 GC equipped flame ionization detector. Helium flow was 2.0 niL/min (constant flow mode), with a 10:1 split ratio. The oven temperature was held at 35°C for 10 min, followed by a ramp to 270°C at 3C/min, followed by a 1.67 minute hold time. The detector temperature was held at 300°C.

Further modifications and alternative embodiments of various aspects of the invention will be apparent to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the general manner of carrying out the invention. It is to be understood that the forms of the invention shown and described herein are to be taken as the presently preferred embodiments. Elements and materials may be substituted for those illustrated and described herein, parts and processes may be reversed, and certain features of the invention may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description of the invention. Changes may be made in the elements described herein without departing from the spirit and scope of the invention as described in the following claims.

Claims

C L A I M S

1. A method comprising:

(a) providing a divided electrochemical cell comprising an anode in a first cell compartment and a cathode in a second cell compartment, wherein the electrochemical cell comprises an electrolyte;

(b) providing an aqueous solution of a reducible sugar and an alkali metal salt as electrolyte into the second compartment

(c) providing electrical energy from an energy source selected from the group consisting of nuclear, hydroelectric, wind, geothermal, and solar power to the

electrochemical cell to apply an electrical potential between the anode and the cathode and through said sugar solution to reduce said sugar to a polyhydric alcohol; and

(d) contacting the polyhydric alcohol with a solid acid condensation catalyst at a temperature in the range from 325 °C to about 425 °C to produce water and an aromatics- rich higher molecular weight hydrocarbons stream having at least 50wt% of aromatics containing hydrocarbon based on the aromatics-rich high molecular weight hydrocarbons stream.

2. A method according to claim 1, further comprising generating the reducible sugar, wherein said generating step comprises:

providing a divided electrochemical cell comprising an anode in a first cell compartment and a cathode in a second cell compartment, wherein the electrochemical cell comprises an electrolyte;

providing a biomass substrate to the first compartment; and

providing electrical energy from an energy source selected from the group consisting of nuclear, hydroelectric, wind, geothermal, and solar power to the

electrochemical cell to apply an electrical potential between the anode and the cathode sufficient to at least partially degrade the substrate to generate a reducible sugar.

3. A method according to any preceding claim, further comprising:

prior to step (d), reacting the polyhydric alcohol with an acidic amorphous silica alumina catalyst at a temperature in the range from 300°C to 400°C to generate a mono- oxygenate, thereby producing a mono-oxygenated stream containing water and organic monooxygenates having a boiling point of at least 40 °C; optionally condensing the monooxygenated stream to liquid phase;

wherein step (d) comprises

contacting the mono-oxygenated stream with a solid acid condensation catalyst at a temperature in the range from 325 °C to about 425 °C producing water and an aromatics- rich higher molecular weight hydrocarbons stream having at least 50wt% of aromatics containing hydrocarbon based on the aromatics-rich high molecular weight hydrocarbons stream.

4. A method according to any preceding claim, wherein the electrolyte in the first compartment comprises sodium hydroxide and/or sulfuric acid.

5. A method according to claim 2, wherein the biomass substrate comprises a lignocellulosic material and/or cellulose.

6. A method according to any preceding claim, wherein the polyhydric alcohol is selected from a group consisting of sorbitol, mannitol, and pentols.

7. A method according to any one of claims 3, 4 or 6, wherein the acidic amorphous silica alumina catalyst has BET surface area of greater than 200 m²/g.

8. A method according to any one of claims 3, 4, 6 or 7, wherein the yield of aromatics-rich hydrocarbons stream is greater than 40% of carbons based on biomass carbons.

9. A method according to any one of claims 3, 4, 6, 7 or 8, wherein the pressure of reacting the polyhydric alcohol with an acidic amorphous silica alumina catalyst is within the range of ambient pressure to about 200psi.

10. A method according to any one of claims 3, 4, 6, 7, 8 or 9, further comprising:

condensing at least a portion of the monooxygenated stream to liquid phase producing an aqueous phase and an organic phase;

removing the aqueous phase from the organic phase;

wherein step (d) comprises contacting the monooxygenates in the second portion of the organic phase having boiling point of at least 40°C and/or non-condensed monooxygenates if any with a solid acid condensation catalyst at a temperature in the range from 275 °C to about 425 °C producing a higher hydrocarbons stream.

11. A method according to claim 10, wherein the organic phase comprises at least one ketone and/or cyclic ether.

12. A method according to any preceding claim, wherein the solid acid condensation catalyst is a ZSM-5 catalyst.

13. A method according to any preceding claim, wherein the acid condensation catalyst is a mineral based acidic catalyst or acidic zeolites.

14. A method according to claim 1 or 2, further comprising

prior to step (d), reacting the polyhydric alcohol with an acidic amorphous silica alumina catalyst at a temperature in the range from 300°C to 400°C thereby producing monooxygenated stream containing water and monooxygenates having a boiling point of at least 40°C;

condensing the monooxygenated stream to liquid phase producing an aqueous phase and an organic phase;

removing at least a portion of aqueous phase from the organic phase to provide a condensed organic stream containing the monooxygenates; and

contacting the monooxygenates having boiling point of at least 40°C in the condensed organic stream with a strong acidic solid at a temperature in the range from 300°C to about 350°C and a pressure in a range from 500 to 1200psi producing a higher hydrocarbons stream containing unsaturated hydrocarbons including olefins and dienes.