A Catalyst Composition for Different Reforming Techniques

Abstract

The present invention provides a catalyst composition comprising different metal oxides wherein the catalyst composition comprising Ce, Cr and Ni oxides and a process for preparation thereof. The catalyst composition is used for different reforming techniques for the production of syn gas (CO+H.sub.2) at the same time this material can be used in fuel cell as a anode for power generation as this synthesized material is having good thermal stability and can sustain various redox reaction cycles also.

Claims

1. A catalyst composition comprising of different metal oxides wherein the catalyst composition comprising Ce, Cr and Ni oxides.

2. The catalyst as claimed in claim 1, wherein said composition comprising Ce, Cr and Ni oxides present in the ratio 1-50% w/w, 20-49% w/w and 1-60% w/w respectively.

3. The catalyst as claimed in claim 1, wherein said catalyst is recyclable and stable upto 800 C. even after sintering at 1400 C.

4. The catalyst as claimed in claim 1, wherein said catalyst is supported or unsupported.

5. The catalyst as claimed in claim 1, wherein said catalyst is useful for oxidative steam reforming, dry and tri reforming, wherein said oxidative reforming is without of a need of a heat source.

6. The catalyst as claimed in claim 1, wherein said catalyst is useful for the production of syn gas and useful for internal as well as external reforming.

7. A process for the preparation of a catalyst composition comprising of different metal oxides wherein the catalyst composition comprising Ce, Cr and Ni oxides comprising the steps of: a. dissolving a nitrate precursor of metal in a solvent to obtain a solution of a metal nitrate precursor; b. dissolving citric acid in the solvent to obtain a solution of citric acid; c. adding the solution of metal nitrate precursor into the solution of citric acid followed by heating at temperature ranging from 100 C. to 190 C. until evaporation of solvent to form a gel; and d. keeping the gel of step (c) in oven at temperature ranging from 100 C. to 190 C. for 24 to 25 hours to form fluffy material of the catalyst followed by crushing fluffy material to powder.

8. The process as claimed in claim 7, wherein said solvent of step is water.

9. The process as claimed in claim 7, wherein said nitrate precursor of metal is selected from Chromium nitrate, Cerium nitrate, and nickel nitrate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0039] FIG. 1: XRD plot of CCN5 catalyst Fresh and Spent comparison

[0040] FIG. 2: Combined XRD Plot of Fresh catalysts

[0041] FIG. 3: Combined XRD Plot of Spent Catalysts

[0042] FIG. 4: BET surface area Plot of CCN Catalysts

[0043] FIG. 5: HRTEM micrograph of fresh CCN catalyst

[0044] FIG. 6: Combined activity plot for S/C1.5 at 800 C., 15000 h.sup.1 GHSV

[0045] FIG. 7: Combined activity plot for S/C2 at 800 C., 15000 h.sup.1 GHSV

[0046] FIG. 8: Comparison plot of sintered and non-sintered catalyst at 800 C., 15000 h.sup.1 GHSV and S/C=1.5 FIG. 9: Activity plot for OSRM at 800 C., 15000 h.sup.1 GHSV

[0047] FIG. 10: Activity plot of DRM for CCN YSZ catalyst at 800 C., 28800 h.sup.1 GHSV

[0048] FIG. 11: Activity plot of Methanol Reforming for CCN YSZ catalyst

DETAILED DESCRIPTION OF THE INVENTION

[0049] The invention will now be described in detail in connection with certain preferred and optional embodiments, so that various aspects thereof may be more fully understood and appreciated.

[0050] To overcome the aforesaid drawbacks in the prior arts, the present invention provides a catalyst composition which does not contain any precious metals in it. Further, catalyst composition of the present invention is tested for stability for upto TOS 500. The catalyst composition of the present invention can work for various reforming technique such as Steam reforming of Methane (SRM), dry reforming of Methane (DRM), Auto thermal reforming of Methane, Tri reforming, etc. The catalyst composition as disclosed in present invention is tested for sintering effect at 1400 C. and found durable at this temperature, this sintering is generally used to fabricate SOFC cell so catalyst can be fabricated into SOFC anode cell. The present invention discloses the composition which can be fabricated into anode cell of SOFC.

[0051] The present invention provides catalyst composition comprising different metal oxides wherein the catalyst is used for different reforming techniques for the production of syn gas (CO+H.sub.2) at the same time this material can be used in fuel cell as a anode for power generation as this synthesized material is having good thermal stability and can sustain various redox reaction cycles also and a process for preparation thereof.

[0052] In an embodiment, the present invention provides a catalyst composition comprising of different metal oxides wherein the catalyst composition comprising Ce, Cr and Ni oxides.

[0053] The catalyst composition comprising Ce, Cr and Ni oxides present in the ratio 1-50% w/w, 20-49% w/w and 1-60% w/w respectively.

[0054] The catalyst is useful for oxidative steam reforming, dry and tri reforming, wherein the oxidative reforming is without of a need of a heat source.

[0055] The catalyst is recyclable.

[0056] The catalyst is stable up to 800 C. even after sintering at 1400 C.

[0057] The catalyst is found as a stable catalyst in reactions up to 1-500 hours and can be used for further more time on stream studies.

[0058] The catalyst is free of noble metals.

[0059] The catalyst is supported or unsupported.

[0060] The catalyst is used for the production of syn gas (H.sub.2 and CO).

[0061] The catalyst gives good conductivity and also possesses good thermal stability.

[0062] The catalyst also acts on a variety substrates like methane, methanol and so on, so multiple fuels can be used for the production of syn gas.

[0063] The catalyst can be used for internal as well as external reforming.

[0064] The catalyst material can be used as an anode.

[0065] In another embodiment, the present invention provides a process for preparation of the catalyst composition comprising the steps of: [0066] a) dissolving a nitrate precursor of metal in a solvent to obtain a solution of a metal nitrate precursor; [0067] b) dissolving citric acid in the solvent to obtain a solution of citric acid; [0068] c) adding the solution of metal nitrate precursor into the solution of citric acid followed by heating at the temperature ranging from 100 C. to 190 C. until evaporation of solvent to form a gel; and [0069] d) keeping the gel of step (c) in oven at the temperature ranging from 100 C. to 190 C. for 24 to 25 hours to form fluffy material of the catalyst followed by crushing fluffy material to powder.

[0070] The metal of step (a) is selected from Cr, Ce, or Ni.

[0071] The solvent used in the process for the preparation of the catalyst composition is water.

[0072] The nitrate precursor of metal of step (a) is selected from Chromium nitrate, Cerium nitrate, and nickel nitrate.

[0073] The catalyst can also be prepared with wet impregnation method as well as co precipitation method found similar catalytic activity and stability.

[0074] Catalyst has been characterized with BET, XRD, and recyclability. Multi functionality and energy balance are important features of the present invention. Also usually for oxidative steam, reforming noble gas is needed, however in the present invention no noble element is used, hence exactly opposite is demonstrated.

[0075] Activity of the catalyst is good for all the reforming techniques with the Partial/Oxidative Steam reforming so that it can be used in SOFC without any need of external energy source.

[0076] Catalytic activity is highly stable and maintained with electrical conductivity and thermal stability with more yield.

[0077] Catalytic activity is high along with electrical conductivity and thermal stability for steam reforming of methane (SRM), Dry reforming (DRM), Oxidative steam reforming (OSRM), Tri Reforming of methane, lower alcohols reforming techniques.

[0078] Following table 1 elaborates all the compositions of catalyst which were synthesized and tested for reforming activity.

TABLE-US-00001 TABLE 1 YSZ-CCN (composition Catalyst composition in SI. fraction %) (wt %) No Catalyst YSZ CCN Ce Cr Ni 1 CCN-YSZ 50 50 25 20 5 (A1) 2 CCN-10 (A2) 0 100 50 40 10 3 CCN-7.5 (A4) 0 100 50 42.5 7.5 4 CCN-5 (A3) 0 100 50 45 5 5 CCN-2.5 (A6) 0 100 50 47.5 2.5 6 CCN-1 (A5) 0 100 50 49 1 7 C-0-CN (B1) 0 100 0 50 50 8 C-1-CN (B2) 0 100 1 49 50

[0079] All the synthesized catalysts are investigated using the techniques like XRD, TEM, BET surface area as well as TGA techniques.

[0080] 2 Vs Intensity profile shown in FIG. 1 for a fresh catalyst which clearly shows the presence of following mixed metal oxides phases like CeO.sub.2, Cr.sub.2O.sub.3, NiO as well as NiCr.sub.2O.sub.4 spinel. It is also evidenced from the XRD data that the phases of Cr.sub.2O.sub.3 are rhombohedral and all other phases of NiO, CeO.sub.2 and NiCr.sub.2O.sub.4 are cubic. The XRD patterns of fresh and spent catalysts are shown in FIG. 2 and FIG. 3 respectively. It is indicated that the samples are crystalline and identified as a mixture of oxides due to those sharp diffraction peaks. As shown in FIG. 1, those diffraction peaks are fully consistent with the standard JCPDS cards of NiCr.sub.2O.sub.4 (No. 89-6615), Cr.sub.2O.sub.3 (No. 84-1616), CeO.sub.2 (No. 34-934) and NiO (No. 89-5881), respectively. FIG. 4 shows BET surface area Plot of CCN Catalysts. N.sub.2 adsorption-desorption isotherms at 250 C. and the pore size distribution (PSD) according the Barrett-Joyner-Halenda (BJH) method for the CCN samples.

[0081] Table 2 shows pore size and PV table.

TABLE-US-00002 TABLE 2 BET Surface Pore Pore S. area size Volume(PV) Coke No Catalyst (m.sup.2/g) .sup.(a) (nm) (cc/g) (%) .sup.(b) 1 CCN YSZ 16.2 3.2 0.03 4.8 2 CCN 5 6.57 1.6 0.03 4.5 3 CCN 7.5 9.9 1.7 0.01 4.4 4 CCN 10 10.76 3.04 0.02 3.2 5 CCN 5 sin 1.3 0.9 0.001 4.6 .sup.(a) represents BET Surface area analysis, .sup.(b) represents TGA analysis of Spent catalyst.

[0082] TGA analysis of spent catalyst has been done and found that there is very negligible coke deposition on the catalysts.

[0083] TEM micrograph demonstrated that the synthesized catalyst nanoparticles are spherical in shape along with well-defined lattice plane with lattice fringes which confirmed the crystallinity of the nanomaterial. The lattice fringes observed in case of FIGS. 5(b) and 5(d) corresponds to interplanar spacing of (220) and (111) plane respectively which confirmed the existence of spinel phase (NiCr.sub.2O.sub.4) of the catalyst. Whereas the lattice fringes observed in the FIGS. 5(c) and 5(e) corresponds to the (012) and (111) planes of Cr.sub.2O.sub.3 and CeO.sub.2 nanoparticles respectively. The interplanar spacing which is observed in TEM images are well match with the measured XRD pattern of the catalyst.

[0084] FIG. 6 graph shows the conversion activity of CH.sub.4 of all the catalyst run over a period of 12 hrs at 800 C., 15000 h1 GHSV and S/C=1.5. Catalyst prepared with 7.5% Ni (CCN7.5), 5% Ni (CCN5) and 10% Ni (CCN10) gave the better activity and the CH.sub.4 conversion is around 97-98%, 93-96% and 89-94% respectively with H.sub.2 selectivity around 75-76% for CCN 7.5, 74-76% CCN 5 and 72-73% for CCN 10.

[0085] FIG. 7 graph shows the conversion activity of CH.sub.4 of all the catalyst run over a period of 12 hrs at 800 C., 15000 h1 GHSV and S/C=2. Catalyst prepared with 7.5% Ni (CCN7.5), 5% Ni (CCN5) and 10% Ni (CCN10) gave the better activity and the CH.sub.4 conversion was close to 97-98.5%, 94-97% and 91-93% respectively with H.sub.2 selectivity around 76-78% for CCN 7.5, 74-76% CCN 5 and 73-75% for CCN 10.

[0086] FIG. 8 graph shows the comparison in conversion activity of CH.sub.4 of the catalyst CCN5 before and after sintering at 1400 C. run over a period of 12 hrs at 800 C., 15000 h1 GHSV and S/C=1.5 and found to be thermally stable, thus can be used as cermet.

[0087] FIG. 9 graph shows the conversion activity of CH.sub.4 of catalyst CCN5 run over a period of 12 hrs, 15000 h1 GHSV varying S/C from 1.5 to 0.5 which is much less than the required Stoichiometric ratio. Thus the catalyst is stable in oxidative conditions also.

[0088] FIG. 10 graph shows the conversion activity of CH.sub.4 and CO.sub.2 of CCN-YSZ catalyst run over a period of 100 hrs at 800 C., 28800 h1 GHSV. Around 80-85% conversion of CH.sub.4 and 85-90% conversion of CO.sub.2 is observed and catalyst is found to be stable throughout the run.

[0089] FIG. 11 graph shows the conversion activity of CH.sub.3OH by CCN-YSZ catalyst over a period of 12 hrs at 500 C., 28800 h1 GHSV and S/C=2. Around 95-99% conversion of CH.sub.3OH is observed and catalyst is found to be stable throughout the run.

[0090] Data generated shows methane conversion is 100% within an hour to syn gas and remains same for 13-14 hours. Energy balance is close to 100%. Process is environmentally friendly because of reduced water production and therefore reduced CO.sub.2 production. Dry reforming of methane and CO.sub.2 tested for 100 hours and 85% conversion is seen at 550 C. and for 12 hours.

EXAMPLES

[0091] Following examples are given by way of illustration therefore should not be construed to limit the scope of the invention.

Example 1: Synthesis of Catalyst

[0092] The catalysts were prepared by citrate gel method, for the preparation nitrate precursors of Ce, Cr and Ni were used (Alfa Aesar). These precursors are dissolved in minimal amount of distilled water. Citric acid is taken in 3:1 molar ratio of total ingredients and it is also dissolved in water. On a heating mantle with a stirrer at 190 C. in citric acid solution, these precursors are slowly added and left for few hours until the water is evaporated and a gel is formed. Addition starts at 100 C. and after addition, it is maintained at 190 C. Now this gel is kept in oven at 180 C. for 24 hours which will result in fluffy material formation. Further it is crushed to powder and is kept in furnace at 800 C. The compositions of Ce, Cr, Ni are mentioned in the proportions described in the table 1.

Advantages of the Invention

[0093] 1. Catalyst is recyclable. [0094] 2. Catalyst is stable up to 800 C. [0095] 3. Catalyst can work even after sintering at 1400 C. [0096] 4. Catalyst is stable in reactions up to 500 hours. [0097] 5. Free of noble metals. [0098] 6. Catalyst is supported or unsupported on YSZ showing similar type of activity and stability. [0099] 7. Nickel Chromate spinel is also forming along with other metal oxides which is a very stable and material for reforming reactions. [0100] 8. Catalyst can be fabricated into Anode cell of SOFC.