WO2021142076A1

WO2021142076A1 - Amended silicates for scavenging and destroying dioxins/furans and other organics in industrial process streams and effluents

Info

Publication number: WO2021142076A1
Application number: PCT/US2021/012439
Authority: WO
Inventors: Thomas K. Gale
Original assignee: Environmental Energy Services, Inc.
Priority date: 2020-01-07
Filing date: 2021-01-07
Publication date: 2021-07-15

Abstract

Herein is disclosed an industrial-gas flow treatment aid that includes a non-activated particulate support carrying a metal oxide coating, such as an iron oxide coating, ferric oxide microparticulates, or a coating of ferric oxide. The particulate support may be clay particles. In one embodiment, the treatment aid includes calcium oxide. In another embodiment, the treatment aid includes a plurality of non-activated particulates carrying ferric oxide and calcium ferric oxide micro-particulates or a coating thereof. Additional embodiments include the preparation of the treatment aid and the process of removing dioxins and/or furans from an industrial-gas flow with the catalytic treatment aid, for example by decomposition or destruction of the dioxins and/or furans to eliminate or substantially reduce the concentration of dioxins and/or furans in the gas flow.

Description

AMENDED SILICATES FOR SCAVENGING AND DESTROYING DIOXINS/FURANS AND OTHER ORGANICS IN INDUSTRIAL PROCESS STREAMS AND EFFLUENTS

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Application No. 62/957,996 filed on January 7, 2020, entitled “Amended Silicates for Scavenging and Destroying Dioxins/Furans and Other Organics in Industrial Process Streams and Effluents,” which is incorporated by reference herein in its entirety for all purposes.

FIELD OF THE INVENTION

[0002] This disclosure relates to a product for destroying dioxins, furans, and other organics, more particularly, destroying polychloro-p-dibenzodioxins (PCDD or DD) and polychlorodibenzofurans (PCDF or DF) (these compounds are hereinafter referred to as "dioxins" and/or “furans”), and various other toxic and/or harmful organics (for example, nonane). Also disclosed are methods for manufacturing such products, and application of the products to effectively scavenge and/or destroy harmful and/or toxic organic compounds. In some cases, the harmful and/or toxic organic compounds may be found within industrial process gasses and effluents. Use of the products may not require addition of process equipment other than that associated with injection of the product. In some cases, the product may be a powder.

BACKGROUND

[0003] Commercial incinerators, such as municipal solid waste, industrial waste, and medical waste incinerators, and cement kilns produce dioxins and furans (PCDD and PCDF) in small quantities. Allowable dioxin release is limited due to their toxicity. These Dioxins, though generally small in concentration, are highly toxic even at the concentrations produced and at the concentration limits regulated. For example, in its final rule, EPA estimated that emission limits for existing medical waste incinerators are expected to produce reductions of 96-97% for dioxins and furans (Fed. Regist. 62(178):48348- 48391). Waste incinerators of all types in the U.S. are regulated via a combination of Federal, State, and Local air permitting agencies and applicable rules. A typical requirement for dioxins and furans is that they be less than 30 ng/m³, as was the case for the Illinois Environmental Protection Agency emission permit limits for the Robbins Resource Recovery Facility (Foster Wheeler Corp, 1997).

[0004] Dioxins collected on or with the ash must be incinerated to destroy the absorbed dioxins. Methods for treating such dioxins-containing fly ash generally involve the thermal decomposition of the dioxin-containing fly ash, for example by heating for 1-2 hours at a temperature between 320 and 400 °C under a reductive atmosphere, or 300-500 °C in the presence of a dioxins formation inhibitor. These fly-ash treatment processes have the drawback that their high treatment temperatures and long treatment times require a large expenditure of energy and cost.

[0005] Alternative procedures for dioxin removal include the injection of powdered limestone (e.g., calcium- based) into the furnace, to destroy dioxins, collecting the spent adsorbent with a dust collector, or injecting activated carbon or similar powder to adsorb dioxins, then incinerating the dioxins-adsorbed along with the adsorbent and fly ash collected. Activated Carbon is a common name for products made from carbon feedstock. The carbon is “activated,” for example by one manufacturing method by heating to about 1000 °C, to produce a large internal surface area. Other methods of activation are known to those of skill in the art. The surface area (macro-, meso-, or, micro-pore surface area, and combinations thereof), may, in some cases, be tailored for a specific application. A high micro-pore surface area is about 3000 to 5000 m²/g, while a high meso-pore surface area is about 500 m²/g. Currently, activated carbon is the most used method to mitigate dioxins/furans from combustion sources. Activated carbon adsorbs dioxins/furans and must subsequently be incinerated, typically along with the fly ash, which can create secondary issues, such as re-release of mercury or other heave metals collected on the fly ash.

SUMMARY

[0006] A first embodiment is an industrial process-gas flow and flue-gas treatment aid in the form of an injected powder that includes a non-activated particulate support carrying an iron- oxide coating.

[0007] A second embodiment is an industrial process-gas flow and flue-gas treatment aid that includes a plurality of clay particles each carrying one or more ferric-oxide microparticles or a coating of ferric oxide, the clay particulates further carrying calcium oxide.

[0008] Another embodiment is an industrial process-gas flow and flue-gas treatment aid that includes a plurality of bentonite, kaolin, montmorillonite, sepiolite, saponite, talc, bauxite, aluminosilicate, vermiculite, perlite, Halloysite, or other clay particulates carrying ferric-oxide and calcium-oxide and/or calcium ferric oxide compound microparticles or coatings thereof.

[0009] Still another embodiment is a process of preparing an industrial process-gas flow and flue-gas treatment aid that includes admixing a particulate support and an iron oxide in a solvent; and then drying the admixture to yield a powder having a mean particulate diameter of about 5 to about 150 microns.

[0010] Yet another embodiment is a process of catalytically destroying the dioxins and/or furans in an industrial process-gas flow or flue gas that includes injecting a treatment aid into the gas that is contaminated with dioxins and or furans; admixing the treatment aid with the dioxins and/or furans in the industrial gas flow; catalytically decomposing the dioxins and/or furans into light, non-toxic gases; and subsequently collecting the treatment aid with the clean ash, containing no dioxins or furans, wherein substantially all such toxins have been destroyed, such that the concentration of dioxins/furans remaining is below any regulatory or permit limits. Hence, the ash does not require incineration, because the dioxins, furans, and other harmful organics will have already been eliminated.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1 is a schematic diagram of an experimental procedure of one embodiment.

[0012] FIG. 2 shows removal efficiency of MCDD and DF by ncP-1 at 180 °C and 0.26s residence time when the treatment aid has been activated at 400 °C.

[0013] FIG. 3 shows removal efficiency of MCDD and DF by the treatment presently disclosed ncP-2 at 180 °C and 0.26s residence time when the treatment aid has been activated at 400 'Ό.

[0014] FIG. 4 shows removal efficiency of MCDD and DF by ncP-1 at 180 °C and 0.13s residence time when the treatment aid has been activated at 200 °C.

[0015] FIG. 5 shows removal efficiency of MCDD and DF by ncP-1 at 250 °C and 0.13s residence time when the treatment aid has been activated at 200 °C.

[0016] FIG. 6 shows removal efficiency of MCDD and DF by ncP-1 at 350 °C and 0.13s residence time when the treatment aid has been activated at 200 °C.

[0017] FIG. 7 shows removal efficiency of MCDD and DF by ncP-1 at 450 °C and 0.13s residence time when the treatment aid has been activated at 200 °C. [0018] FIG. 8 shows removal efficiency of MCDD and DF by the treatment aid presently disclosed ncP-2 at 180 °C and 0.13s residence time when the treatment aid has been activated at 400 ^qC.

[0019] FIG. 9 shows removal efficiency of MCDD and DF by the treatment aid presently disclosed ncP-2 at 250 °C and 0.13s residence time when the treatment aid has been activated at 400 'Ό.

[0020] FIG. 10 shows removal efficiency of MCDD and DF by the treatment aid presently disclosed ncP-2 at 350 °C and 0.13s residence time when the treatment aid has been activated at 400 °C.

[0021] FIG. 11 shows removal efficiency of MCDD and DF by the treatment aid presently disclosed ncP-2 at 450 °C and 0.13s residence time when the treatment aid has been activated at 400 °C.

[0022] FIG. 12 shows removal efficiency of MCDD and DF by activated carbon at 180 °C and 0.13s residence time.

[0023] FIG. 13 shows a comparison table of presently disclosed ncP-2 performance compared with alternative effective sorbents.

DETAILED DESCRIPTION

[0024] Herein are described compositions, methods of their manufacture, and methods of their use where the compositions are active for the catalytic decomposition of dioxins and furans in combustion-derived gases. The compositions generally include particles amended with an iron and/or other oxide.

[0025] In one embodiment, the composition is a flue-gas treatment aid that includes a particulate support carrying an iron-oxide coating. In many embodiments, the flue-gas treatment aid may be non-activated, such that it has not been treated, prior to use, to increase its surface area. The particulate support may be a mineral compound. In other embodiments, the particulate support may be selected from one or more of an aluminate, a silicate, an aluminosilicate. The aluminate, silicate, and/or aluminosilicate can be naturally occurring mineral compounds, manufactured aluminates, silicates, and/or aluminosilicates, cleaned and/or recycled materials, or mixtures thereof. In some embodiments, the particulate support can be one or more of bentonite, montmorillonite, kaolinite, hectorite, beidellite, saponite, nontronite, volkonskoite, sauconite, stevensite, a synthetic smectite, rectonite, vermiculite, illite, micaceous minerals, makatite, kanemite, octasilicate (illierite), magadiite, kenyaite, attapulgite, palygorskite, sepiolite, allophane, quartz, talc, or a mixture thereof. In yet another embodiment, the particulate support can be limestone.

[0026] The oxide may be selected from various elements suitable for decomposing dioxins and furans. In some embodiments the oxide is a metal oxide, for example calcium or iron oxide. The iron oxide can include iron in any readily available oxidation state. In some embodiments, the iron is iron(ll), iron(lll), or a mixture thereof. In one embodiment, the iron oxide includes ferrous ions, in another the iron oxide includes ferric ions, in still other embodiments the iron oxide includes a mixture of ferrous and ferric ions. In most embodiments, the oxidation state of iron in the iron oxide may be estimated based on a valency balance within the iron-oxide composition.

[0027] In some embodiments, the iron oxide can be FeO, Fe₃0 , Fe₂0₃, or a mixture thereof. In other embodiments, the iron oxide can be a ferrous oxide, for example FeO or wustite. In another embodiment, the iron oxide can be a ferric oxide, for example Fe₂0₃, hematite, red iron oxide, maghemite, colcothar, iron ochre, or rust. In still other embodiments, the iron oxide can be a ferrous/ferric oxide, for example Fe₃0₄, or magnetite. In many embodiments, the iron oxide is a ferric oxide, such as Fe₂0₃.

[0028] The iron oxide can be or include an iron alloy. That is, the iron oxide can include an oxide of iron and additional oxidized elements, for example, transition metals. As used herein, the term iron alloy refers to a mixture of iron and another metal where at least the iron is an oxide, preferably where the iron and the other metal are oxides. As used in this context, the term alloy has a different and distinct meaning from the common usage of alloy in the metallurgical arts. In one particular embodiment, the iron alloy includes iron and a transition metal selected from the group consisting of V, Cr, Mn, Co, Ni, Cu, Zn, and a mixture thereof. In another particular embodiment, the iron alloy include iron and tin, optionally including a transition metal selected from the group consisting of V, Cr, Mn, Co, Ni, Cu, Zn, and a mixture thereof. The iron alloy can be, for example, a solid solution of oxides of iron and the transition metal(s) (e.g., wherein the iron oxide is the solvent and the transition metal oxide(s) is the solute), a heterogeneous mixture of the iron oxide and the transition metal oxide(s) (i.e., a mixture of distinct iron oxide particulates and transition metal oxide particulates; notable, herein heterogeneous does not mean an incomplete mixing but a solid product that includes at least two distinct materials), and/or a homogeneous phase of an iron-(transition metal)-oxide. Specific compositions can include, for example, a Mn₂0₃-Fe₂0₃ solid solution, a Co₃0 -Fe₂0₃ solid solution, a Co0-Fe₂0₃ solid solution, a Mn₂0₃-Fe₂0₃ admixture, a Co₃0 -Fe₂0₃ admixture, Mn₂0₃ carried on Fe₂0₃, Co₃0 carried on Fe₂0₃, a Mn₂0₃-Co₃0₄-Fe₂0₃ solid solution, a material having the composition (M)_xFe_yO_z, where M is selected from V, Sn, Cr, Mn, Co, Ni, Cu, Zn, and a mixture thereof, and x is an integer ranging from 0 to 5, y is an integer ranging from 1 to 10, and z is an integer ranging from 1 to 15, preferably wherein z is an integer that equals one half of the total cationic state of M_xFe_y. Preferably, the iron alloy includes a first row transition metal. In other embodiments, the iron alloy can include second or third row transition metals as necessary to support or enhance the catalytic activity of the material. In still another embodiment, the iron alloy can include post-transition metals, lanthanides or actinides. When the iron oxide includes an iron alloy, the alloy preferably includes at least 50 wt. %, 60 wt.%, 70 wt.%, 80 wt.%, or 90 wt.% iron, based on total metal content. In another embodiment, the iron alloy preferably includes at least 50 atom%, 60 atom%, 70 atom%, 80 atom%, or 90 atom% iron, based on total metal atom content. For reference, when the iron oxide material is all in the form of Fe₂0₃, the material includes 100 wt.% iron and 100 atom% iron.

[0029] In still another example, the iron oxide can include a cationic component and an anionic component, preferably wherein the anionic component includes an oxide of iron as Fe(ll), Fe(lll) or a mixture thereof. The cationic component can include an alkali metal, an alkaline earth metal, a quaternary pnictide, or a mixture thereof. Preferably, the cationic component includes an alkali metal and/or an alkaline earth metal. In one embodiment, the iron oxide includes Na, K, Mg, and/or Ca. In still another embodiment, the iron oxide has the composition XFeO_y wherein X is Na, K, Mg, and/or Ca, and y is an integer from 1 to 4. In yet another embodiment, the iron oxide includes the elements C_aM_bRb_gO_d where a is an integer ranging from 1 to 5, b is an integer ranging from 0 to 5, g is an integer ranging from 1 to 15, d is an integer ranging from 1 to 30, and X and M are selected from those provided above (e.g., X can be Na, K, Mg, and/or Ca, and M can be V, Cr, Mn, Co, Ni, Cu, and/or Zn).

[0030] The composition may include various ratios of particulate and oxide. In some embodiments the particulate is about 50 to 95% of the composition by weight, for example greater than 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or 90%, and less than about 95%, 90%, 85%, 80%, 75%, 70%, 65%, 60%, or 55%. In some embodiments the one or more oxides may comprise about 5% to 50% of the composition by weight, for example greater than 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, or 45%, and less than about 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, or 10%. In some embodiments, the composition may have a first oxide and a second oxide wherein the first oxide is about 50% to 5% of the composition by weight, and the second oxide is about 0.1% to 20% of the composition by weight. For example, the first oxide is about 50%, 49%, 48%, 47%, 46%, 45%, 44%, 43%, 42%, 41%, 40%, 39%, 38%, 37%, 36%, 35%, 34%, 33%, 32%, 31%, or 30%, the second oxide is about 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20%, and the particulate is about 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, or 70%. Preferably, the flue-gas treatment aid has a composition that includes about 35 wt.% to about 55 wt.% of the one or more oxides, and about 65% to about 50% particulate. In one embodiment, the flue-gas treatment aid includes about 35 to about 45 wt.% of the one or more oxide and about 65 to 55 wt.% of the particulate support. In additional embodiments, the flue gas treatment aid can include at least 0.5 to about 5% of a second oxide. In one embodiment, the first oxide is iron oxide, for example Fe2C>3, and the second oxide is calcium oxide.

[0031] In another example, the second oxide of the industrial process-gas flow and flue gas treatment aid can be an alkaline oxide or alkaline hydroxide. The alkaline oxide or hydroxide can be sodium hydroxide, potassium hydroxide, magnesium oxide, magnesium hydroxide, calcium oxide, calcium hydroxide, or a mixture thereof. In one preferable embodiment, the alkaline oxide or hydroxide is a calcium oxide and/or a calcium hydroxide. More preferably, the alkaline oxide is calcium oxide: CaO or quick lime. The flue-gas treatment aid can include the alkali oxide or alkaline hydroxide as a solid solution with the iron oxide and/or as a particulate admixed with the iron oxide. In one embodiment, the treatment aid includes a particulate admixture of the alkali oxide or alkaline hydroxide and iron oxide, which is an admixture of the respective particulates.

[0032] The treatment aid can include about 0.5 wt.% to about 5 wt.% of the alkaline oxide or hydroxide, wherein the balance is, preferably, the iron oxide and the particulate support. Furthermore, the treatment aid can consist of (or consist essentially of) the iron oxide, the particulate support and the alkaline oxide or hydroxide. In most embodiments, the treatment aid may include a solvent (e.g., water) used in the preparation of the treatment aid, adsorbed from the environment (e.g., humid air), or intentionally added to affect storage, clumping, flow, or other characteristics other than reactivity with dioxins and or furans in the gas flow. In such embodiments, the treatment aid is still understood to consist of the iron oxide, the particulate support, and, preferably, the alkaline oxide or hydroxide. In one preferable embodiment, the treatment aid includes 0.5 wt.% to about 2.5 wt.% CaO.

[0033] In another example, the treatment aid includes a plurality of particulate substrates each carrying one or more ferric oxide microparticulates or a coating of ferric oxide. In this example, the particulate substrates further carry or are coated with calcium oxide. In this example, the treatment aid can include, or consist of, about 5 wt.% to about 50 wt.% ferric oxide, about 0.5 wt.% to about 2.5 wt.% calcium oxide, and about 47.5 wt.% to about 94.5 wt.% substrate. Preferably, the treatment aid includes, or consists of, about 35 wt. % to about 40 wt.% ferric oxide, about 0.5 wt.% to about 2.5 wt.% calcium oxide, and about 57.5 wt.% to about 64.5 wt.% substrate. In a preferable embodiment, the particulate substrates are clay particulates each carrying one or more ferric-oxide microparticles or a coating of ferric oxide.

[0034] In still another example, the treatment aid can include a plurality of clay particles carrying calcium ferric oxide microparticles or a coating thereof. The calcium ferric-oxide microparticles or coating, preferably, has the formula Ca_xFe 03_+x wherein x is a value between about 0.01 and about 0.1. Preferably, x is a value between about 0.025 and about 0.075.

[0035] Another embodiment is a process of preparing the above described treatment aid. The process can include admixing a particulate support and an iron oxide, preferably, in or in the presence of a solvent; and then drying the admixture and milling as needed. Preferably, the resultant powder has a mean particulate diameter of about 2 to about 150 microns.

[0036] In one example of the process, the particulate support and iron oxide can be admixed with water. The amount of water in relation to the particulate support and iron oxide can be greater than about 10 wt.%, 20 wt.%, 30 wt.%, 40 wt.%, 50 wt.%, 60 wt.%, 70 wt.%, 80 wt.%, 90 wt.%, or 100 wt.%. In one embodiment, the water is limited to provide a paste or “dry” admixture that can be processed by physical mixers such as pin mixers, kneaders, or extruders. In another embodiment, the water is added to provide a slurry of the particulate support and the iron oxide, herein a slurry is understood to be a heterogeneous liquid or suspension of fine particles in the solvent (e.g., water). Preferably, the process includes dispersing the iron oxide (and optionally calcium oxide) in water and then adding this dispersion to the particulate support.

[0037] In several embodiments, the particulate support is, preferably, a phyllosilicate. In one embodiment, the phyllosilicate is a swellable clay (e.g., montmorillonite and bentonite). In another embodiment, the phyllosilicate is a non-swellable clay (e.g., talc, kaolinite, and sepiolite).

[0038] In one embodiment the iron oxide is ferric oxide. In another embodiment, the iron oxide can be formed in-situ by admixing the particulate support and an iron oxide precursor (e.g., an iron chloride or iron powder) in an atmosphere or solvent that facilitates the conversion of the iron oxide precursor to an iron oxide.

[0039] In still another embodiment, the process can further include admixing with a calcium oxide. Preferably, the calcium oxide is contemporaneously added and mixed with the particulate support and iron oxide. In another embodiment, the calcium oxide can be premixed with the iron oxide prior to admixing with the particulate support. In still another embodiment the calcium oxide can be added to an admixture of the particulate support and the iron oxide. In yet another embodiment, the calcium oxide can be admixed with the particulate support prior to the addition of the iron oxide. In most embodiments, the calcium oxide can be added as a powder, slurry, or solution, preferably in the same solvent as used in the admixing of the particulate support and the iron oxide.

[0040] The drying of the admixture (e.g., removal of the water) can be, for example, by thermal distillation of the solvent, spray drying, vacuum distillation, or other industrially- applicable means. In one embodiment, the admixture is dried to a point wherein the treatment aid includes less than about 20 wt.%, 15 wt.%, 10 wt.%, 5 wt.% or 1 wt.% residual solvent. In the case of spray drying, spray drying can be used to produce a small particle size for effective product performance. In still another embodiment, drying of the admixture may take place in a fluidized-bed dryer or static dryer, or other type of dryer using heated air flow to dry the product, and the dry product would be subsequently milled.

[0041] The disclosed composition may be manufactured using a variety of methods. In some embodiments, the method may include mixing a clay, a first oxide and, optionally, a second oxide with water to yield a flowable mixture; filtering the flowable mixture by filter press, while, optionally, recycling the water; drying the filtered mixture via any feasible method, such as baking, fluidized-bed dryer, shaker dryer, etc; milling the dried mixture via any method feasible, such as a pin mill, jet mill, hammer mill, etc; thereby creating the claimed composition. In another embodiment, the method may include: mixing a dry clay and a first oxide in dry form, and optionally, a third oxide in dry form; adding water to promote agglomeration of particles; allowing the optional second oxide to form a hydroxide; mixing with high shear force, for example with a mixers, pug mills, kneaders, etc,; drying the sheared mixture via any feasible method, such as baking or fluidized-bed dryer or shaker dryer; and milling the dried mixture via any method feasible, such as a pin mill, block mill, jet mill, hammer mill etc. to create the disclosed composition. [0042] In another embodiment, the treatment aid can be used to remove dioxins and or furans from an industrial gas flow, including a flue gas. The process can include injecting a treatment aid into an industrial gas flow containing dioxins and/or furans. In many embodiments, the industrial gas flow contains dioxins and/or furans at a concentration that exceeds a permitted or regulatory minimum concentration. The treatment aid may then be admixed with the dioxins and/or furans in the gas flow. Therein, oxidizing, decomposing, or otherwise catalytically destroying all or substantially all of the dioxins and/or furans; and thereafter removing the flue-gas treatment aid from the gas flow by collecting it with the industrial process ash. In most embodiments, catalytic destruction of substantially all of the dioxins and/or furans in the gas flow may result in reduction of dioxins and/or furans to levels that are below permitted and/or regulatory minimums. In some embodiments, catalytic destruction of substantially all of the dioxins and/or furans in the gas flow may result in reduction of dioxins and/or furans to within an acceptable concentration range, which may be lower than a permitted and/or regulatory minimum.

[0043] In some embodiments, the treatment aid is used at varying temperatures. In various embodiments, the presently disclosed treatment aid may be used at different temperatures ranging from about <100 °C to over about 450 °C. In one embodiment, DDs and DFs are exposed to the presently disclosed treatment aid at low temperatures. For example, a low temperature range may be between about 50 °C and 350 °C. In another embodiment, DDs and DFs are exposed to the presently disclosed treatment aid at high temperatures. In many embodiments, ‘high temperature,’ as used herein may be between about 350 °C and 500 °C. At both low and high temperatures, the presently disclosed treatment aid may help to remove DDs and DFs through catalytic degradation.

[0044] Preferably, the treatment aid catalytically destroys dioxins and/or furans in the industrial gas flow. In one embodiment, the treatment aid is a catalyst that facilitates the oxidation of dioxins and/or furans in the gas flow. In some circumstances, the catalytic decomposition of the dioxins and/or furans in the gas flow includes the reaction of the dioxins and/or furans with oxygen (0 ) in the gas flow, the rate of oxidation of which is catalytically increased by from about 2-fold to 10, 20, 30, 50, or more orders of magnitude by the treatment aid. In other embodiments, the catalytic destruction is strictly a decomposition (breaking of bonds) of the dioxin/furans on the surface of the catalyst, in the absence of free oxygen being present in the process gas stream. The treatment aid may destroy various forms of dioxins and/or furans in the gas flow by either or both of these decomposition mechanisms, such that, in contrast to using activated carbon, it is not necessary to incinerate any fly ash.

[0045] The treatment aid may be suspended in the industrial gas flow, provided as a medium through which the gas flow must pass (such as in a catalyst bed, in the form of plates or honeycombs), or otherwise positioned within the gas flow. The treatment aid may also be injected as a dispersible powder (potentially once through) into the industrial gas-flow ductwork. The location of injection is preferably downstream from the combustion or other high- temperature gas source, more preferably downstream from any process equipment such as an candle filter, SCR, or air heater, but upstream of the electrostatic precipitator, fabric filter, and/or wet or dry scrubber. More preferably, the treatment aid is injected into an industrial gas flow that is at a temperature of about 120 to about 450 °C.

[0046] While the treatment aid may be applicable in any circumstance where dioxin and/or furan emissions can occur, the process preferably includes the injection of the treatment aid into the industrial gas flow or flue gas produced by a cement kiln, a waste incinerator, a hazardous waste incinerator, a municipal solid waste incinerator, medical-waste incinerator, biomass combustor, biomass gasifier, gasifier using coal as a feedstock or other organic fuel type, or other industrial process. Preferably, the process includes the injection into gas flow produced by a waste or biomass incinerator.

EXAMPLES

Example 1 - Dioxin decomposition effectiveness of catalytic treatment aids

[0047] Experiments were performed to compare the effectiveness of various non-carbon metal-oxide and metal sulfide catalysts on clay or other inorganic supports with activated carbon at decomposing and completely destroying dioxins and furans in flue gas or other industrial gas flows.

Experimental Setup

[0048] As illustrated in Fig. 1 , testing of the dioxin/furan destructive capability of non carbon metal oxide and metal sulfide catalyst materials were performed in a reactor GCFID system using a “titration method.” Each sample (activated carbon, non-carbon PRODUCT 1 (“ncP-1” metal sulfide supported on clay), and non-carbon PRODUCT 2 (“ncP2” a dioxin/furan decomposition catalyst comprising about 60% clay [bentonite], about 39% Fe 0 , and about 1% CaO), was held in a fixed-bed while gases were passed through it. A spike of non-chlorinated (to avoid toxicity for the tests) representative dioxin and furan species was injected into the gas and through the fixed bed. The dioxin/furan spike escaping through the fixed bed was measured by gas chromatography.

[0049] The titration method used here included sequential injections of the reaction mixture into the carrier gas stream at 20 minute intervals. This allows for the analysis of gas effluent leaving the system at the sample bed or reactor vessel. Each injection was 0.6 mI volume of the 1-monochloro dibenzo-p-dioxins (MCDD) and dibenzofuran (DF) solution in nonane, to yield the gas-phase concentration of 27 and 36 ppm, respectively. MCDD was used as a general representation of DDs while DF was used for DFs. A sorptive/catalytic sample bed was composed of a mixture of sand and sample material to ensure proper dilution of the active phase and prevent creation of pressure drops and hot spots. The ratio of sand to test sample was approximately 5:1 (5+1 g for 0.26s residence time and 2.5+0.5 g for 0.13s residence time).

Quality Assurance - Calibration

[0050] For each test run of the samples (either metal sulfide formulations, or the presently disclosed iron oxide formulation - referred to herein as presently disclosed ncP-2) and activated carbon, all component lines of the Reactor-GCFID system were calibrated based on the preferred reactor temperatures (180, 250, 300, 350, 400 °C).

[0051] Calibration was performed in the following order. First, the reactor system was calibrated by injection of DF/DD mix ten times, with each injection passing through an empty sample bed. Peak areas of the DF and DD signals were recorded and computed for the statistical standard deviation. Next, the transfer line system was calibrated via bypassing the reactor mode by injection of the DF/DD mix approximately 10 times. Peak areas of the DF and DD signals were recorded and computed for the statistical standard deviation. Then, the reactor system containing sand, only, as a catalytic sample bed was calibrated by injection of DF/DD mix. This serves as the BLANK of the experiment for the desired temperature of the study. The injection was repeated approximately 25-30 times. Peak areas of the DF and DD signals were recorded.

[0052] In between calibration steps, the reactor vessel was thoroughly cleaned with solvent, lab grade detergent and distilled water with final rinsing of methanol and acetone solvents, and then dried in oven at 400 °C overnight, prior to use for the next steps. [0053] After the calibration steps described above, the dioxin/furan decomposition catalysts or activated carbon mixed with sand was tested. This was done by injecting DF/DD mix for approximately 25-30 times. Peak areas of the DF and DD signals were recorded.

Example 2 - Establishing baseline capacity of treatment aids

[0054] Initial testing of ncP-1 and one embodiment of the presently disclosed treatment aid, ncP-2, was performed at a gas phase reagents residence time in the sample bed of 0.26s, to establish the overall baseline capacity of both ncP-1 and presently disclosed ncP-2. For these experiments, both were activated prior to the reaction by heating in air at 400 °C for 1 hour. The results of those experiments are shown in Figs. 2 and 3.

[0055] As shown in Fig. 2, ncP-1 showed relatively poor removal efficiency of DFs with a fast deactivation during the first 7 injections, while 60-80% of DDs were removed during first 17 injections, with slowly declining activity starting after 12 injections. Based on these results and observations, the pretreatment temperature for ncP-1 was decreased to 200 °C for the remaining tests of this sample.

[0056] As shown in Fig. 3, presently disclosed ncP-2 was found to be very efficient for the removal of both MCDD and DF (100%). Based on these results, all remaining testing for presently disclosed ncP-2 was conducted at a shorter residence time of 0.13s.

Example 3 - Testing performance of ncP-1

[0057] Figs. 4-7 show results of the performance of ncP-1 samples (pretreated at

200°C) in the removal of PCDD and PCDF at various temperatures ranging from 180-450 °C and a residence time of 0.13s. Decrease of the pretreatment temperature of the samples resulted in improved performance at 180 °C (Figs. 2 and 4). The removal efficiency at 180°C reaches a steady state at approximately 70% for DDs and approximately 30% for DFs. Increasing the reaction temperature to 250 °C (Fig. 5) results in a drop of the removal efficiency to approximately 20% for both DDs and DFs.

[0058] Such a decrease in activity with increasing temperature may indicate that the removal efficiency in the lower temperature region (180-250 °C) occurs primarily due to the adsorption on the surface of the supported metal sulfide. With increasing temperature, the equilibrium between the gas phase and adsorbed PCDD/Fs shifts towards desorption processes, resulting in an overall decrease of PCDD/F retention on the solid material. [0059] Further increase of the reaction temperature to 350 °C resulted in a change of operation mode of the treatment aid from sorption mechanism to catalytic destruction. This conclusion was based on the observation of increased removal efficiency of the ncP-1 material, reaching destruction efficiency of approximately 70% for DDs and 50% for DFs (Fig. 6). However, further increase of the reaction temperature to 450 °C decreased the destruction efficiency (Fig. 7). This is most likely a result of a transformation of the metal sulfide active form to a less active form at the elevated temperature.

Example 4 - Testing performance of presently disclosed ncP-2

[0060] Figs. 8-11 show results of the performance of the presently disclosed ncP-2 samples (pretreated at 400 °C) in the removal of DDs and DFs at various temperatures ranging from 180-450 °C and a residence time of 0.13s. Despite the change in the residence time from 0.26s to 0.13s, this material showed similarly high activity at 180°C, with a 100% removal of PCDD and PCDFs from the gas stream (Fig. 8). Increase of the reaction temperature to 250 °C (Fig. 9) resulted in a decrease in activity to approximately 60%, at steady state conditions. As in the case of the ncP-1 sample, such decrease in performance with increasing temperature in the low-temperature region may indicate an adsorption mechanism of removal in addition to catalytic degradation. Unlike ncP-1 , both DDs and DFs are removed with the same yield over the presently disclosed ncP-2 sample.

[0061] Further increase of the reaction temperature to OdO'Ό (Fig. 10) resulted in a change of the DD and DF removal mechanism, with catalytic degradation becoming the dominant mechanism. In fact, removal activity was sustained at the 90% level for both studied groups of compounds (DDs and DFs). Elevation of the reaction temperature to 450 °C did not improve the degradation of DDs (removal yield at approximately 90%) but instead decreased steady state degradation yield of DFs to approximately 50% (Fig. 11).

[0062] The results showed that the presently disclosed ncP-2 activity is extremely high and the iron-oxide catalyst is able to effectively remove and destroy dioxins and furans at temperatures anywhere from < 100 °C to over 450 °C, without decomposing or losing effectiveness.

Example 5 - Comparison of performance of ncP-1 and presently disclosed ncP-2

[0063] The results indicated that ncP-1 is much less efficient than the presently disclosed ncP-2 material at both lower and higher temperature regimes. Presently disclosed ncP-2 is a superior material with high destruction efficiency. Overall, ncP-1 may be less active than presently disclosed ncP-2 for the removal of PCDD/F in both regimes (adsorption and catalytic).

Example 6 - Comparison of performance of catalytic treatment aids with alternative effective sorbent

[0064] The performance of both non-carbon products, ncP-1 and ncP-2, were also compared to that of commercially available activated carbon at 180°C (Fig. 12). Unlike metal oxide and metal sulfide catalysts supported on non-activated clay supports, activated carbon was found to be selective in the removal of aliphatic hydrocarbons (nonane), representing other components of the combustion exhaust, while the activity towards removal of PCDD/F was lower. In fact, nonane was removed with close to 100% efficiency over activated carbon (complete disappearance of the peak in chromatogram), while removal efficiency was unmeasurable for the non-carbon catalytic materials (saturated peak). The removal of DF was approximately 95% and removal of DDs was approximately 70% at steady state. Overall, presently disclosed ncP-2 iron-oxide catalyst formulation performed better than activated carbon (100% removal for both DDs and DFs) (Fig. 13). Interestingly, there was an opposite trend of adsorption between non-carbon catalytic materials and activated carbon: for both catalytic materials, removal of chlorinated “dioxins” was more effective than non-chlorinated (MCDD vs DF), while on activated carbon, non-chlorinated was more effectively retained. These results indicate that the non-carbon catalytic powders (and especially presently disclosed ncP-2) would perform even more effectively at catalytically destroying polychlorinated compounds than the superior results shown here for removal of non-chlorinated compounds.

[0065] Fig. 13 shows a table comparing performance for dioxin and furan destruction of presently disclosed ncP-2 to a non-carbon sorbent material and activated carbon. As shown, presently disclosed ncP-2 was much more effective at mitigating the dioxins and furans. The presently disclosed ncP-2 was able to catalytically destroy the dioxins and furans regardless of their concentration and at all temperatures. In addition, repeated laboratory tests (over 30 exposure runs) showed that the presently disclosed ncP-2 did not deactivate, while the other effective catalytic powder material (active component - metal sulfide) deactivated after 12 runs.

[0066] While multiple embodiments are disclosed, still other embodiments of the present invention will become apparent to those skilled in the art from the detailed description. As will be apparent, the invention is capable of modifications in various obvious aspects, all without departing from the spirit and scope of the present invention. Accordingly, the detailed description is to be regarded as illustrative in nature and not restrictive. [0067] All references disclosed herein, whether patent or non-patent, are hereby incorporated by reference as if each was included at its citation, in its entirety. In case of conflict between reference and specification, the present specification, including definitions, will control.

[0068] Although the present disclosure has been described with a certain degree of particularity, it is understood that the disclosure has been made by way of example, and changes in detail or structure may be made without departing from the spirit of the disclosure as defined in the appended claims.

Claims

WHAT IS CLAIMED:

1. An industrial-gas flow treatment aid comprising: a non-activated particulate support carrying a catalytically-active, iron oxide coating on an external surface thereof.

2. The treatment aid of claim 1 , wherein the non-activated particulate support is a mineral compound.

3. The treatment aid of claim 1 or claim 2, wherein the non-activated particulate support is selected from a group consisting of an aluminate, a silicate, an aluminosilicate, and a mixture thereof.

4. The treatment aid of any of claims 1 -3, wherein the non-activated particulate support is selected from a group consisting of bentonite, montmorillonite, kaolinite, hectorite, beidellite, saponite, nontronite, volkonskoite, sauconite, stevensite, a synthetic smectite, rectonite, vermiculite, illite, micaceous minerals, makatite, kanemite, octasilicate (illierite), magadiite, kenyaite, attapulgite, palygorskite, sepiolite, allophane, quartz, talc, and mixtures thereof.

5. The treatment aid of any of claims 1 -4, wherein the non-activated particulate support is selected from bentonite, montmorillonite, vermiculite, illite, mica, attapulgite, palygorskite, saponite, allophane, quartz, and mixtures thereof.

6. The treatment aid of any of claims 1 -5, wherein the non-activated particulate support is bentonite and/or saponite and/or kaolinite.

7. The treatment aid of any of claims 1 -6, wherein the iron oxide in the coating includes iron in an oxidation state selected from the group consisting of iron(ll), iron(lll), and a mixture thereof.

8. The treatment aid of any of claims 1 -7, wherein the iron oxide in the coating is selected from the group consisting of FeO, Fe₃0₄, Fe₂0₃, and a mixture thereof.

9. The treatment aid of any of claims 1 -8, wherein the iron oxide in the coating is Fe₂0₃.

10. The treatment aid of any of claims 1 -9, wherein the iron oxide in the coating is an iron alloy.

11 . The treatment aid of claim 10, wherein the iron alloy includes iron and a transition metal selected from the group consisting of V, Cr, Mn, Co, Ni, Cu, Zn, and a mixture thereof.

12. The treatment aid of claim 11 , wherein the iron alloy includes a transition metal content that is at least 50 wt%, 60 wt.%, 70 wt.%, 80 wt.%, or 90 wt.% iron.

13. The treatment aid of any of claims 1 -12, comprising about 5 wt.% to about 50 wt.% of the iron oxide.

14. The treatment aid of any of claims 1-13, further comprising an alkaline oxide or alkaline hydroxide.

15. The treatment aid of claim 14, wherein the alkaline oxide or hydroxide is selected from the group consisting of sodium hydroxide, potassium hydroxide, magnesium oxide, magnesium hydroxide, calcium oxide, calcium hydroxide, and a mixture thereof.

16. The treatment aid of claim 15, wherein the alkaline oxide or hydroxide is a calcium oxide and/or a calcium hydroxide.

17. The treatment aid of claim 16, wherein the alkaline oxide is CaO.

18. The treatment aid of claim 14 comprising about 0.5 wt.% to about 5 wt.% of the alkaline oxide or hydroxide.

19. The treatment aid of claim 18 comprising about 0.5 wt.% to about 2.5 wt.% CaO.

20. A treatment aid comprising: a plurality of particulate substrates each carrying one or more ferric oxide micro particulates or a coating of ferric oxide, the particulate substrates further carrying calcium oxide.

21 . The treatment aid of claim 20, comprising about 5 wt. % to about 50 wt.% ferric oxide, about 0.5 wt.% to about 2.5 wt.% calcium oxide, and about 47.5 wt.% to about 94.5 wt.% substrate.

22. The treatment aid of claim 21 , comprising about 35 wt. % to about 40 wt.% ferric oxide, about 0.5 wt.% to about 2.5 wt.% calcium oxide, and about 57.5 wt.% to about 64.5 wt.% substrate.

23. A treatment aid comprising: a plurality of particulate substrates carrying calcium ferric oxide micro particulates or a coating thereof.

24. The treatment aid of claim 23, wherein the calcium ferric oxide has a formula of Ca_xFe 03_+x wherein x is a value between about 0.01 and about 0.1.

25. A process of preparing a treatment aid comprising: admixing a particulate support and an iron oxide in a solvent; and then drying the admixture to yield a powder having a mean particulate diameter of about 5 to about 150 microns.

26. The process of claim 25, wherein the solvent includes water.

27. The process of claim 25 or claim 26, wherein the particulate support is a phyllosilicate.

28. The process of any of claims 25-27, wherein the iron oxide is ferric oxide.

29. The process of any of claims 25-28, wherein the admixing further includes a calcium oxide.

30. The process of any of claims 25-29 wherein the admixing involves dry mixing of powders with sufficient water to add a dispersion of the iron oxide and calcium oxide across a surface of the clay particles.

31 . A process of removing dioxins and/or furans from an industrial-gas flow comprising: injecting a treatment aid into a gas flow that is contaminated with dioxins and or furans; admixing the treatment aid and the dioxins and/or furans in the gas flow; catalytically oxidizing and/or decomposing the dioxins and/or furans; and collecting treatment aid with an industrial process ash, totally free of toxic organics, including dioxins and furans.

32. The process of claim 31 , wherein the treatment aid is injected into an industrial- gas flow that is at a temperature of about 120 to about 450 °C.

33. The process of claim 31 or claim 32, wherein the process occurs in a cement kiln, a waste incinerator, a hazardous waste incinerator, a municipal solid waste incinerator, medical waste incinerator, biomass combustor, biomass gasifier, gasifier using coal as a feedstock or other organic fuel type, or other industrial process.