WO2012006478A2

WO2012006478A2 - Self-contained, mobile methanol synthesis plant

Info

Publication number: WO2012006478A2
Application number: PCT/US2011/043270
Authority: WO
Inventors: Steven Phillip Atkins; Brandon Doss
Original assignee: Arizona Board Of Regents, Acting For And On Behalf Of, Northern Arizona University
Priority date: 2010-07-07
Filing date: 2011-07-07
Publication date: 2012-01-12
Also published as: WO2012006478A3; WO2012006478A9

Abstract

The present invention relates to a portable, self-contained system and process for producing methanol from carbon dioxide and hydrogen gases. The system is designed to be portable, so that it may be readily transported to and operated at various sites wherein carbon dioxide and/or hydrogen gases are produced and/or collected, and those gases reacted to form methanol. In a preferred embodiment, the system of the invention is transported to a site where it is permanently or temporarily installed and placed into operation.

Description

SELF-CONTAINED, MOBILE METHANOL SYNTHESIS PLANT

[0001] RELATED APPLICATION DATA

[0002] This application claims priority to U.S. Provisional Patent

Application No. 61/362,239 filed on July 7, 2010, the entirety of which is incorporated herein by reference thereto.

[0003] FIELD OF THE INVENTION

[0004] The invention relates to the field of sustainable energy, and the production of methanol, which is useful as a fuel and as a basic chemical.

[0005] BACKGROUND OF THE INVENTION

[0006] Sustainable energy production, energy security, affordability, price volatility, carbon taxation, carbon dioxide emissions, and effective waste utilization at existing industrial plants and commercial fermentation sites currently is of significant concern to many governmental entities, companies and individuals. Methanol, and compounds which may be made from methanol, such as di-methyl ether, synthetic gasoline and plastics, may be used as direct replacements of their fossil fuel derived equivalents.

[0007] BRIEF SUMMARY OF THE INVENTION

[0008] The present invention relates to a portable, self-contained system and process for producing methanol from carbon dioxide and hydrogen gas. The system is designed to be portable, so that it may be readily transported to and commissioned at various sites wherein carbon dioxide and/or hydrogen gases are produced and/or collected, and those gases reacted to form methanol. In a preferred embodiment, the system of the invention is transported to a site where it is permanently or temporarily installed and commissioned (placed into operation).

[0009] The system of the invention is designed so that various organizations and business establishments could have the system easily and quickly delivered and set up into an operative sate on their premises, to utilize and process into methanol excess gases that may be available at that premises for various reasons. For example, breweries which produce carbon dioxide as a result of the fermentation process in which beer is produced often have a wish to dispose of the carbon dioxide in an environmentally- friendly manner. The system of the present invention provides a way for breweries to readily have a methanol synthesis system installed on or near the brewery premises, to convert process to methanol excess carbon dioxide captured in the fermentation.

[0010] In a specific embodiment, the invention is a process and apparatus for synthesizing carbon-neutral fuels derived from captured (and preferably concentrated) atmospheric carbon dioxide and hydrogen. The hydrogen gas is ideally obtained from hydrolysis of water and via use of renewable electricity. The system of the invention produces methanol liquid, which is a carbon-neutral transportation fuel, and can be burned in most existing vehicles without modification. The primary synthesis product is methanol, an alcohol with chemical and physical properties that are nearly identical to ethanol. Methanol can be blended with gasoline up to 20% (M20) and burned in any unmodified internal combustion engine or at blends up to 85% (M85) in flex fuel vehicles. While methanol can be used directly as an automotive fuel, the invention can also include a means to further process methanol into di-methyl ether (DME), an excellent diesel fuel and propane substitute, synthetic gasoline and even carbon-negative plastics such as ethylene and propylene.

[0011] BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The present invention will now be described in more detail, with reference to preferred embodiments, given by way of examples, and illustrated in the accompanying drawings in which:

[0013] FIGURE 1 is a schematic representation of a process and device according to a preferred embodiment of the invention using a recirculating loop.

[0014] FIGURE 2 is a schematic representation of a process and device according to an embodiment of the invention without a recirculating loop.

[0015] FIGURE 3 is a graphical representation of the conversion of CO₂ to methanol as a function of temperature and pressure at GHSV = 10 000 h ¹.

[0016] FIGURE 4 is a graphical representation of the conversion of CO₂ to methanol as a function of space velocity and pressure, T = 240 °C.

[0017] FIGURE 5 is a graphical representation of the space-time yield

(STY) as a function of pressure and space velocity, T = 240 °C.

[0018] FIGURE 6 is a graphical representation of an analysis of the purity of three types of methanol: (A) reagent grade methanol; (B) calibration solution made from 0.01%(v/v) ethanol (RT=2.2 min), isopropanol (RT= 2.9 min), isopentanol (RT = 7.9 min), and 0.05% (v/v) 1-butanol (RT = 6.9 min); and (C) synthetic methanol produced at 1400 psi and 4500 h^"1 (enlarged to show detail).

[0019] DETAILED DESCRIPTION OF THE INVENTION

[0020] The device of the invention is designed to be self-contained, easily transportable, and may be operated at existing sites that emit carbon dioxide (for example, fermentation plants, breweries, etc.) and/or sites with abundant (renewable), low cost electricity, which may be used to disassociate water in order to obtain the requisite hydrogen. The device of the invention consumes carbon dioxide from the atmosphere or carbon dioxide destined to be emitted into the atmosphere (e.g., from smokestacks, fermentation processes, etc.), water, and electricity only. Its only outputs are methanol, water, and heat, but further processing may convert methanol to DME, gasoline and/or plastics. When powered by renewable electricity, the portable methanol synthesis plant of the invention is capable of producing a renewable, carbon-neutral, liquid transportation fuel that can be used in all gasoline engines.

[0021] The invention provides carbon-emitting entities with a new way to sequester carbon dioxide into a valuable product, rather than permitting it to vent to the atmosphere. With respect to industrial ethanol production facilities, the invention has the capability to significantly increase the alcohol fuel production capacity of the industry at only a modest capital investment.

[0022] The invention is designed to operate at various scales, depending on the size of the carbon dioxide and/or hydrogen source and desired methanol output. By way of example, and without intending to limit the invention, the smallest, economically viable plant size may be 12,000 gal/yr of methanol production.

[0023] In a preferred embodiment, the entire system is essentially pre- assembled on a platform or some other movable structure, so that once the system is transported to the site where it will be commissioned (operated), very little further assembly will be required to render the system operational. Components may be compartmentalized for easy transport by truck, and for "plug and play" operation at fermentation sites or other sites with a carbon dioxide and/or hydrogen source.

[0024] In a preferred embodiment of the invention, all that will be needed to commence operation once the system has been delivered is the hookup of gas feedlines for CO₂ and/or H₂. [0025] The system of the invention is optionally equipped with a storage tank for collecting the methanol produced. The storage tank may be unitary to the system, i.e., incorporated into the system delivered to the site, or it may be external to the system. In the event that the storage tank is external to the system, in a preferred embodiment, only hoses, tubing and/or piping composed of material that is inert (non- reactive to and non-dissolvable by) to methanol is attached to the exit portal of the system of the gas-liquid separator component of the system, and liquid methanol is collected in the storage tank as it is drawn off from the system.

[0026] The system of the invention is mobile and transportable, meaning that it can readily be prefabricated and delivered to a site where it is intended to be used, with minimal set-up materials, parts and labor required. In a preferred embodiment, no further set-up is required other than providing a source of power such as electricity or a battery to power the components of the system (such as the heater and pressurizing equipment), and to open valves to cause the starting materials (hydrogen and carbon dioxide gases) to flow through the system for reaction in the synthesis reactor.

[0027] The transportability of the system of the invention is made possible by any means by which most or all of the components of the system can be delivered to the site of operation already assembled together in a single package. For example, the system can be packaged in a shipping container, with the various components actually secured to one or more inner surfaces of the container. Alternatively, the system can be preassembled on a platform that can be placed on the floor of the container. Yet another alternative is to secure the preassembled system onto a wheeled platform, or build the system onto a wheeled platform; in either case, the system can be permanently or removably (temporarily) secured to the wheeled platform. A non limited example of a wheeled platform is a flat bed trailer. Still yet another alternative is to use a trailer having sides and a roof in place of a flat bed trailer. Yet another alternative is to incorporate the system into a truck or other self-propelled vehicle.

[0028] The system may include a power generating device, such as a generator, for use in powering the system in place of using electricity or for use as an emergency backup should the main source of power fail.

[0029] An embodiment of a device of the invention comprises five (5) main components or systems, as follows: a carbon dioxide recovery system, a gas recirculation system, a heat-exchanging system, a synthesis reactor, and a distillation system. The synthesis reactor is provided with a catalyst, preferably a fixed-bed catalyst, to catalyze the reaction between the hydrogen and carbon dioxide gases to form methanol. Examples of catalysts which are preferred include Cu/Zn catalysts, particularly Cu/Zn/ A1₂0₃.

[0030] In a preferred embodiment of the invention, the device further includes a mechanism or loop for recirculating unreacted carbon dioxide and hydrogen gas that exit the methanol synthesis reactor, so that these unreacted gases are transported back into the methanol synthesis reactor as starting materials for the synthesis of methanol. The mechanism for recirculating includes pipes and pumps, as well as pressure regulators and check valves to facilitate the return of unreacted CO₂ and ¾ to the synthesis reactor. Figure 1 is a schematic illustration of an embodiment of the invention including a recirculating loop. Figure 2 is a schematic illustration of a methanol synthesis device without the recirculating loop.

[0031] In yet another embodiment of the invention, the device further comprises a hydrogen electrolyzer system for hydrolyzing water (such as with electricity) to cause it to break into hydrogen gas and oxygen gas. The hydrogen gas produced thereby is then used in the methanol synthesis device and process of the invention.

[0032] Components may be compartmentalized for easy transport by truck, and for plug-and-play operation at fermentation sites or other sites with a CO₂ and/or hydrogen/electricity source. With this invention, the conversion of carbon dioxide to methanol is estimated to be 95% or greater, and product purity is estimated to be 99.5% or greater.

[0033] In one embodiment, the synthesis reactor typically operates in the range of about 1400 to about 1800 psi. One typical operating condition would be about 1400 psi at about 240 °C. In another specific embodiment, the synthesis reactor is operated at 1800 psi at 240 °C.

[0034] Experimental Section.

[0035] The following is a discussion of various experiments carried out to demonstrate certain aspects of the invention. Unless otherwise noted, all pressure units are pounds per square inch (psi), all GHSV units are liters synthesis gas per liter catalyst per hour (L_syngasL_cat ¹ h^"1, also abbreviated as h^"1), and temperature units are in degrees Celsius (°C). The commercial catalyst used in this study, Katalco 51-8, was donated by Johnson Matthey, Inc. The Cu/ZnO/A^Cb catalyst was received as solid cylindrical pellets with a packing density of 1190 kg/m³. [0036] Synthesis gas was premixed at 75 mol % H₂ and 25 mol % CO₂ and was obtained locally from Praxair, Inc. The cylindrical reactor was constructed in- house from 316SS with 12 inches length and an internal diameter of 1 inch. All pressurized gas lines were 316SS 0.25 inch o.d. tubing and sealed with Swagelok fittings. Gas flow rates were regulated using Brooks 5850 mass flow controllers, which were calibrated with a certified mass flow meter from Alicat Scientific. Reactor pressure was maintained by a back pressure regulator monitored via a pressure transducer with digital display. The reactor temperature was maintained by an external, electrical heating block and a PID temperature controller. The catalyst bed temperature was measured during reactions using a type K thermocouple positioned within the reactor itself, near the center of the catalyst bed. Figure 2 shows a schematic of the reactor system described here.

[0037] For all experiments, 0.1 L of catalyst was loaded as received into the reactor and was reduced at 180 °C, 100 psi, and 500 h^"1 for 24 hours in an atmosphere of 2% ¾ and 98% N₂. The reactor was then flushed withH₂ for 1 hour before introducing the synthesis gas. Experiments were performed by establishing T, P, and GHSV conditions followed by a 15 minute equilibration time to achieve steady state. Reaction products were collected for 20 minutes of continuous synthesis.

[0038] Experimental conditions are summarized in Table 1, and all data is represented as the average of triplicate measurements, unless otherwise noted.

[0039]

Table 1. Experimental Conditions for Methanol Synthesis catalyst particle pressure space velocity load (kg) size (psi) temperature (°C) (L/L_cat/h)

0.06 Full 1000-1400 220-260 10000

0.10 Full 1000-1800 240 3300-8300

0.10 16/30 mesh 1000-1800 240 3300-8300

[0040] Synthesis products were purified by simple distillation to determine conversion efficiency, reported as molar CO₂ conversion and space-time yield (STY). Sample distillates were first analyzed by FT-IR to confirm methanol as the major product, then by capillary gas chromatography to identify and to quantify any byproducts that may be present in the finished sample. The FT-IR was a Varian Excalibur 3100 with a single bounce Pike ATR accessory. The two gas chromatographs used for purity analysis were a Varian Saturn 2100T for identification of byproducts by mass spectrometry and a Shimadzu GC-14A with a flame ionization detector for quantification of byproducts. In addition, the reactor exhaust stream was analyzed by FT-IR spectroscopy to determine the amount of carbon monoxide (CO) that was formed.

[0041] Results and Discussion

[0042] I. Methanol Yield and Conversion Analysis. Reactor productivity was evaluated by CO2 conversion (mol MeOH/mol CO2) and STY (kgMeOH/Lcat/h). The first suite of experiments was performed in order to determine the optimum temperature for methanol synthesis. For these experiments, GHSV was held constant at 10 000 h^"1; temperature was fixed at either 220, 240, or 260 °C; and pressure was varied from 1000 to 1400 psi. Summarized in Figure 3, the results show little effect of temperature on methanol yield for the 1000 and 1200 psi data sets. However, at 1400 psi there is a maximum methanol yield at 240 °C; this was therefore chosen as the set point reaction temperature for all subsequent experiments. There are no error bars in Figure 3 as this data set was not taken in triplicate.

[0043] The second suite of experiments was conducted in order to observe the effects of pressure and space velocity on CO2 conversion and STY. As mentioned above, the reactor temperature was set to 240 °C. Pressures of 1000, 1400, and 1800 psi were explored at GHSV values of 8300, 5000, and 3300 h^"1. Fi gure 4 summarizes the results, which show a monotonic decrease in CO2 conversion with increasing GHSV and a sharp increase with pressure up to 1800 psi.

[0044] II. Methanol Purity and Byproduct Analysis.

[0045] Following confirmation by FT-IR, the synthesized methanol was analyzed for purity and presence of byproducts by capillary gas chromatography. Following simple distillation, 1.0 μΐ., of product methanol was injected onto a DB-5 GC column. Comparison was made to reagent grade methanol (Fisher Scientific) and to a calibration solution made of reagent methanol spiked with 0.01% (v/v) each of ethanol, isopropanol, isopentanol, and 0.05% (v/v) 1-butanol as an internal standard. For quantitative analysis, the synthetic methanol was also spiked with 0.05% (v/v) 1-butanol as an internal standard prior to injection.

[0046] Representative chromatograms (Figure 6) show the presence of 6 minor byproducts in the distillate methanol that, after quantification, represent a total concentration less than 0.05% (v/v). On the basis of retention time correlations with the calibration standards and library search results using NIST MS Search 2.0, the trace impurities were identified as ethanol, isopropanol, 1-propanol, 2-butanol, 1-butanol, and 2-methyl-l-propanol, all of which are acceptable byproducts that should have little or no effect on combustion properties or engine performance when used in modern vehicles.

[0047] Results of exhaust gas measurements by FT-IR are summarized in

Table 2. Measured at 1400 psi, it was found that carbon monoxide is a major component of the exhaust stream having a total molar concentration of 7.9% at 5000 h^"1 and 12.7% at 3300 h^"1.

[0048]

Table 2. Selected Results for Methanol Synthesis Characterization

pressure GHSV yield H₂ conv. CO2 conv. CO byproducts

(psi) (h-¹) (wt %) (mol %) (mol %) (mol %) (vol %)

1000 3300 33.8 ± 3.6 1.8 ± 0.3 5.81 ± 0.8

5000 31.5 ± 1.1 1.3 ± 0.1 3.97 ± 0.3

8300 25.9 ± 1.0 0.9 ± 0.1 2.56 ± 0.3

1400 3300 43.7 ± 0.3 3.2 ± 0.1 9.7 ± 0.4 7.9

5000 41.1 ± 0.8 2.7 ± 0.1 8.0 ± 0.2 12.7 0.017

8300 34.5 ± 0.9 1.7 ± 0.1 5.1 ± 0.4

1800 3300 49.0 ± 0.9 4.8 ± 0.3 14.3 ± 0.9

5000 45.6 ± 1.6 3.9 ± 0.2 1 1.8 ± 0.7 0.032

8300 41.0 ± 2.2 2.9 ± 0.2 8.8 ± 0.7

H₂ conversion calculated as molar ratio of methanol produced to total ¾ flow through rreeaaccttoorr.. ^bbCC00₂₂ ccconversion calculated as molar ratio of methanol produced to total CO₂ flow through reactor.

[0049] Overall, the results obtained were promising with respect to scale- up and commercial implementation of the process described here. Methanol weight % yields were quite high, as much as 43% on a carbon basis; byproducts in the finished methanol were exceptionally low, less than 0.05% by volume; exhaust gas analysis reveals a carbon monoxide level between 8 and 13% on a molar basis. We confirmed that methanol yield increases continually with pressure.

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Claims

What is claimed is;

1. A mobile, self-contained system for synthesizing methanol comprising:

(a) a first apparatus for producing methanol; and

(b) a second apparatus for transporting the first apparatus from one location to another physical location.

2. The mobile, self-contained system of claim 1, wherein the first apparatus comprises:

(a) a system for supplying hydrogen gas and carbon dioxide gas to a synthesis reactor for reacting the hydrogen gas and the carbon dioxide to form methanol;

(b) a recirculating loop for transporting back to the synthesis reactor hydrogen gas and carbon dioxide remaining in the synthesis reactor after formation of methanol.

3. The mobile, self-contained system of claim 2, wherein the synthesis reactor is equipped with means for heating and pressurizing its contents.

4. The mobile, self-contained system of claim 3 further comprising a gas-liquid separator for separating the methanol from the hydrogen gas and carbon dioxide gas remaining in the synthesis reactor after formation of the methanol.

5. The mobile, self-contained system of claim 4 further comprising an apparatus for producing hydrogen gas.

6. The mobile, self-contained system of claim 2, wherein the second apparatus is selected from the group consisting of:

a shipping container;

a wheeled platform having the first apparatus removably secured thereto;

a wheeled platform having the first apparatus permanently secured thereto;

an open trailer containing the first apparatus;

a closed trailer containing the first apparatus; and

a truck or other self-propelled vehicle having the first apparatus secured thereto.

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7. A process for synthesizing methanol comprising transporting the mobile, self- contained system of claim 2 to a site where carbon dioxide is produced or collected, and introducing the carbon dioxide to the system and reacting the carbon dioxide with hydrogen gas to produce methanol.

8. The process of claim 7 wherein the site is a brewery.

9. A process for synthesizing methanol comprising transporting the mobile, self- contained system of claim 2 to a site where hydrogen gas is produced or collected, and introducing the hydrogen gas to the system and reacting the gas with carbon dioxide to produce methanol.

10. A process for synthesizing methanol comprising introducing to the mobile, self- contained system of claim 2 and reacting carbon dioxide gas and hydrogen gas at pressure in the range of about 1400 to about 1800 psi at a temperature in the range of about 220 to about 260 °C.

11. The process of claim 10 wherein the pressure is about 1400 psi and the temperature is about 240 °C.

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