Non noble metal based diesel oxidation catalyst

Abstract

Disclosed is a cheap and efficient non noble metal based catalyst for the oxidation of diesel or hydrocarbons, its synthesis and its application for diesel oxidation at low temperature. The catalyst comprises a mixed oxide of manganese and cerium, or manganese, cerium and zirconium. The catalyst has improved water and sulphur tolerance.

Claims

1. A diesel oxidation catalyst comprising a mixed oxide of A and B, wherein A is Mn and B is Ce or a mixture of Ce and Zr, said catalyst comprises oxide of A in the range of 1-23.314% by weight of the catalyst and oxide of B in the range of 76.686-99% by weight of the catalyst, wherein the catalyst is devoid of noble-metal, and the BET surface area of the catalyst is 150-160 m.sup.2/g with a pore volume of about 0.381 cm.sup.3/g; said catalyst is prepared by a process comprising: a) mixing salt of A and salt of B in water or a mixture of water and an acid to obtain a solution; b) adjusting pH of the solution obtained in step (a) in the range of 7-12; c) heat treating the solution of (b) to a temperature in the range of 100-200 C. for 15-120 minutes to obtain a reaction mixture; d) cooling and filtering the reaction mixture to obtain a residue; and e) washing and calcinating the residue obtained in step (d) at a temperature in the range of 300-800 C. for 1-5 hours to obtain the diesel oxidation catalyst.

2. The catalyst according to claim 1, wherein the salt of A and B is selected from the group consisting of nitrate, acetate.

3. The catalyst according to claim 1, wherein the acid used is nitric acid.

4. A method for using a diesel oxidation in oxidation of propene and carbon monoxide or mixture thereof from diesel engine exhaust, said method comprising the steps of: i) heating said catalyst at 500 C. for 1 hr in flow of 10% O.sub.2 in He followed by cooling to a temperature range of 25 C. to 50 C.; and ii) passing a mixture of carbon monoxide, oxygen and helium gas or a mixture of propene, oxygen and helium gas of said catalyst, wherein gas hourly space velocity of the mixture of gases is in the range of 20,000 h.sup.1 to 100,000 h.sup.1; wherein the catalyst comprises a mixed oxide of A and B, wherein A is Mn and B is Ce or a mixture of Ce and Zr, said catalyst comprises oxide of A in the range of 1-60% by weight of the catalyst and oxide of B in the range of 40-99% by weight of the catalyst, wherein the catalyst is devoid of noble-metal, and the BET surface area of the catalyst is 150-160 m.sup.2/g with a pore volume of about 0.381 cm.sup.3/g.

5. The catalyst according to claim 1, wherein the catalyst oxidizes carbon monoxide (50% conversion) at a temperature in the range of 30 to 250 C.

6. The catalyst according to claim 1, wherein the catalyst exhibits sulphur tolerance with oxidation of carbon monoxide (50% conversion) at a temperature in the range of 200 to 300 C.

7. The catalyst according to claim 1, wherein the catalyst exhibits water tolerance with oxidation of carbon monoxide (50% conversion) at a temperature in the range of 220 to 300 C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1: TEM images of catalyst prepared in Example 3.

(2) FIG. 2: depicts the diesel (propene) oxidation activity of the catalysts in comparison to Pt catalyst.

(3) FIG. 3: depicts diesel oxidation (propene) activity at 50000 h.sup.1 GHSV

(4) FIG. 4: Diesel oxidation (propene) activity at 100000 h.sup.1 GHSV

(5) FIG. 5: Water tolerance of catalyst prepared in Example 3 (propene)

(6) FIG. 6: Sulfur tolerance of catalyst prepared in Example 3.

(7) FIG. 7: Oxidation activity (Propene+CO) of the catalyst prepared in Example 3

(8) FIG. 8: Depicts the (CO) diesel oxidation activity of the catalysts in comparison to Pt catalyst.

(9) FIG. 9: Diesel oxidation activity (Propene) of catalyst prepared in Example 5

(10) FIG. 10: Sulfur tolerance (Propene) of catalyst prepared in Example 5.

(11) FIG. 11: Water tolerance of (Propene) catalyst prepared in Example 5.

(12) FIG. 12: Diesel oxidation activity (CO) of catalyst prepared in Example 5

(13) FIG. 13: Sulfur tolerance of catalyst (CO) prepared in Example 5.

(14) FIG. 14: Water tolerance of catalyst (CO) prepared in Example 5.

(15) FIG. 15: Diesel oxidation activity (CO) of catalyst prepared in Example 6

(16) FIG. 16: Diesel oxidation activity (CO) of catalyst prepared in Example 7

DETAILED DESCRIPTION OF THE INVENTION

(17) 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.

(18) The present invention provides a diesel oxidation catalyst comprising a mixed oxide of A and B, wherein A is Mn and B is Ce or a mixture of Ce and Zr, said catalyst comprises A in the range of 1-60% by weight of the catalyst and B in the range of 40-99% by weight of the catalyst, wherein the catalyst is devoid of noble-metal and is having Mn particle size of 50-70% particles <1 nm; said catalyst is prepared by a process comprising: a) mixing salt of A and salt of B in water or a mixture of water and an acid to obtain a solution; b) adjusting pH of the solution obtained in step (a) in the range of 7-12; c) heat treating the solution of (b) to a temperature in the range of 100-200 C. for 15-120 minutes to obtain a reaction mixture; d) cooling and filtering the reaction mixture to obtain a residue; and e) washing and calcining the residue obtained in step (d) at a temperature in the range of 300-800 C. for 1-5 hours to obtain the diesel oxidation catalyst.

(19) The diesel oxidation catalyst is prepared by modified co-precipitation method and hydrothermal treatment with different molar ratios of salts of A and B.

(20) The BET surface area of the diesel oxidation catalysts is >150 m.sup.2/g with a pore volume of 0.381 cm.sup.3/g for Mn.sub.0.5Ce.sub.0.5O.sub.2.

(21) The catalyst was tested for diesel oxidation using propene, carbon monoxide as model compounds of diesel exhaust and sulphur tolerance and its activity was compared with 1 wt % Pt/Al.sub.2O.sub.3 as reference catalyst.

(22) In another embodiment of the present invention, the catalyst oxidizes carbon monoxide (50% conversion) at temperature in the range of 30 to 250 C.

(23) The diesel oxidation of the catalyst is studied by estimating propene and CO oxidation in a quartz tubular reactor. The detailed protocol is provided in example 9.

(24) In another aspect, the MnCe catalyst shows lower light off temperature compared to Pt/Al.sub.2O.sub.3 and shows 100% conversion at 200 C. for propene and 120 C. for CO which is comparable with that of Pt/Al.sub.2O.sub.3.

(25) With reference to FIG. 2, diesel oxidation activity of the catalyst prepared in Example 3 shows 100% propene conversion at 300 C. in presence of water, exhibiting the water tolerance of the catalyst of the present invention.

(26) The present invention, the diesel oxidation activity of catalyst shoes 100% propene conversion at 200 to 300 C. in presence of SO.sub.2, referring to FIG. 6.

(27) The present invention, the oxidation activity of catalyst shows 100% propene conversion at 220 to 300 C. at higher gas velocities (50000 h.sup.1), referring to FIG. 7.

EXAMPLE

(28) The following examples are given by way of illustration of the working if the invention is actual practice and shall not be construed to limit the scope of the present invention in anyway.

Example 1

(29) Ce(NO.sub.3).sub.3:6H.sub.2O (12.623 g) and 0.798 g of Mn(OAc).sub.2:4H.sub.2O were dissolved in 80 mL deionized water. To this solution, NH.sub.4OH (10% v/v in water) solution was added dropwise with constant stirring till pH 10 was obtained. The mixture was stirred additionally for 24 h at room temperature. The mixture was then transferred to 300 mL teflon-lined stainless steel autoclave and kept static at 120 C. for 40 min and cooled to room temperature. The final reaction mixture was filtered and washed with water. The final residue was dried at room temperature followed by drying at 80 C. for 12 h. Then it was calcined at 500 C. for 5 h at the rate of 2 C. min.sup.1.

Example 2

(30) Ce(NO.sub.3).sub.3:6H.sub.2O (12.623 g) and 3.054 g of Mn(OAc).sub.2: 4H.sub.2O were dissolved in 80 mL deionized water. To this solution, NH.sub.4OH (10% v/v in water) solution was added dropwise with constant stirring till pH 10 was obtained. The mixture was stirred for additionally 24 h at room temperature. The mixture was transferred to 300 mL teflon-lined stainless steel autoclave and kept static at 120 C. for 40 min and cooled to room temperature. The final reaction mixture was filtered and washed with water. The final residue was dried at room temperature followed by drying at 80 C. for 12 h. Then it was calcined at 500 C. for 5 h at the rate of 2 C. min.sup.1.

Example 3

(31) 12.623 g Ce(NO.sub.3).sub.3: 6H.sub.2O and 7.126 g of Mn(OAc).sub.2: 4H.sub.2O was dissolved in 80 mL deionized water. To this solution NH.sub.4OH (10% v/v in water) solution was added dropwise with constant stirring till pH 10. The mixture was stirred for additionally 24 h at room temperature. The mixture was transferred to 300 mL teflon-lined stainless steel autoclave and kept static at 120 C. for 40 min and cooled to room temperature. The final reaction mixture was filtered and washed with water. The final residue was dried at room temperature followed by drying at 80 C. for 12 h. Then it was calcined at 500 C. for 5 h at the rate of 2 C. min.sup.1.

Example 4

(32) The catalyst prepared in Example 3 was characterized by HR-TEM using Tecnai FEI G2 microscope, using an accelerating voltage of 300 kV. For TEM analysis, a sample was dispersed in isopropanol by an ultrasonic bath and deposited on a coated 200 mesh Cu grid. The results are shown in FIG. 1. The TEM analysis showed that majority of manganese particles (50-70%) are <1 nm size.

Example 5

(33) Ce(NO.sub.3).sub.3:6H.sub.2O (30.563 g), Zr(NO.sub.3):6H.sub.2O (7.957 g) and Mn(OAc).sub.2:4H.sub.2O (9.970) was dissolved in 300 mL deionized water and 14 mL conc. HNO.sub.3 acid. To this NH.sub.4OH (10% v/v in water) solution was added dropwise with constant stirring till pH 10. The mixture was stirred additionally for 24 h at room temperature. The mixture was transferred to 300 mL teflon-lined stainless steel autoclave and kept at 120 C. for 40 min and cooled to room temperature. The final reaction mixture was filtered and washed with water. The final residue was dried at room temperature followed by drying at 80 C. for overnight. Then it was calcined at 500 C. for 5 h at the rate of 2 C. min.sup.1.

Example 6

(34) Ce(NO.sub.3).sub.3:6H.sub.2O (20.156 g), Zr(NO.sub.3):6H.sub.2O (5.297 g) and Mn(OAc).sub.2:4H.sub.2O (6.571 g) was dissolved in 120 mL deionized water and 5 mL Conc. HNO.sub.3 acid. To this solution NH.sub.3OH (10% v/v in water) solution was added dropwise with constant stirring till pH 10. The mixture was stirred additionally for 24 h at room temperature. The final reaction mixture was filtered and washed with water. The final residue was dried at room temperature followed by drying at 80 C. for overnight. Then precipitate was calcined at 500 C. for 5 h at the rate of 2 C. min.sup.1.

Example 7

(35) Ce(NO.sub.3).sub.3:6H.sub.2O (10.193 g), Zr(NO.sub.3):6H.sub.2O (2.676 g) was dissolved in 120 mL deionized water and 7 mL Conc. HNO.sub.3 acid. To this solution NH.sub.4OH (10% v/v in water) solution was added dropwise with constant stirring till pH 10. The mixture was stirred additionally for 24 h at room temperature. The final reaction mixture was filtered and washed with water. The final residue was dried at room temperature and followed by drying at 80 C. for overnight. Then precipitate was calcined at 500 C. for 5 h at the rate of 2 C. min.sup.1. To this calcined material 200 ml deionised water was added to form slurry. To this slurry Mn(OAc).sub.2:4H.sub.2O (5.329 g) in 30 mL deionized water was added. To this solution NH.sub.4OH (10% v/v in water) solution was added dropwise with constant stirring till pH 10. The mixture was stirred additionally for 24 h at room temperature. The final reaction mixture was filtered and washed with water. The final residue was dried at room temperature followed by drying at 80 C. for overnight. Then precipitate was calcined at 500 C. for 5 h at the rate of 2 C. min.

Example 8

(36) The manganese content in the catalyst was estimated by ICP-AES using Spectra Arcos instrument. 20 mg sample was dissolved in 10 mL aqua regia by an ultrasonic bath and diluted to 100 mL after digestion on hot plate at 80 C. The results are shown below:

(37) TABLE-US-00001 Catalysts prepared in Example Mn wt. % By ICP-AES 1 3.917 2 13.358 3 24.314

Example 9

(38) The diesel oxidation activity of the catalyst prepared in Example 3 was tested in down flow reactor. Reaction was carried out in a quartz tubular reactor (inner diameter 4 mm) at atmospheric pressure. The catalyst (0.5 g) was diluted with commercial silica gel of 60-120 mesh (2 g) and loaded in the quartz reactor. The reactor was heated with the help of electrically heated furnace. Initially catalyst was heated at 500 C. for 1 h in flow of 10% O.sub.2 in He and then reactor was cooled to 50 C. The reaction was carried out by passing 300 ppm propene+5% O.sub.2, and He gas as a balance. The total flow of the gases was controlled by mass flow controllers to get desired gas hourly space velocity of 20,000 h.sup.1. The concentrations of the inlet and outlet gases were simultaneously monitored using Micro GC (Agilent 3000 A), fitted with molecular sieves to detect different gases (MS 5 A, for O.sub.2, CO), quadrupole mass spectrometer (Hiden, HPR 20) for CO.sub.2 (44), CO (29), C.sub.3H.sub.6 (41). The activity was compared with 1% Pt/Al.sub.2O.sub.3 (commercial composition prepared in house by impregnating aqueous solution of platinum chloride on -Al.sub.2O.sub.3) under identical reaction conditions and the results are given in FIG. 2. The figure shows that the (propene) oxidation activity of catalyst prepared in example 3 is comparable with Pt/Al.sub.2O.sub.3 with better low temperature activity compared to Pt/Al.sub.2O.sub.3 and almost comparable temperature for 100% propene conversion.

Example 10

(39) The diesel oxidation activity of the catalyst prepared in Example 3 was tested in down flow reactor. Reaction was carried out in a quartz tubular reactor (inner diameter 4 mm) at atmospheric pressure. Catalyst (0.5 g) was diluted with commercial silica gel of 60-120 mesh (2 g) and loaded in the quartz reactor. The reactor was heated with the help of electrically heated furnace. Initially catalyst was heated at 500 C. for 1 h in flow of 10% O.sub.2 in He and then reactor was cooled to 50 C. The reaction was carried out by passing 300 ppm propene+5% O.sub.2, and He gas as a balance. The total flow of the gases was controlled by mass flow controllers to get desired gas hourly space velocity of 50,000 h.sup.1. The concentrations of the inlet and outlet gases were simultaneously monitored using Micro GC (Agilent 3000 A), fitted with molecular sieves to detect different gases (MS 5 A, for O.sub.2, CO), quadrupole mass spectrometer (Hiden, HPR 20) for CO.sub.2 (44), CO (29), C.sub.3H.sub.6 (41). The results of the activity are given in FIG. 3. Diesel oxidation activity of catalyst prepared in example 3 showed 100% propene conversion at 230 C.

Example 11

(40) The diesel oxidation activity of the catalyst prepared in Example 3 was tested in down flow reactor. Reaction was carried out in a quartz tubular reactor (inner diameter 4 mm) at atmospheric pressure. Catalyst (0.5 g) was diluted with commercial silica gel of 60-120 mesh (2 g) and loaded in the quartz reactor. The reactor was heated with the help of electrically heated furnace. Initially catalyst was heated at 500 C. for 1 h in flow of 10% O.sub.2 in He and then reactor was cooled to 50 C. The reaction was carried out by passing 300 ppm propene+5% O.sub.2, and He gas as a balance. The total flow of the gases was controlled by mass flow controllers to get desired gas hourly space velocity of 1,00000 h.sup.1. The concentrations of the inlet and outlet gases were simultaneously monitored using Micro GC (Agilent 3000 A), fitted with molecular sieves to detect different gases (MS 5 A, for O.sub.2, CO), quadrupole mass spectrometer (Hiden, HPR 20) for CO.sub.2 (44), CO (29), C.sub.3H.sub.6 (41). The results of the activity are given in FIG. 4. Diesel oxidation activity of catalyst prepared in Example 3 showed 100% propene conversion at 250 C.

Example 12

(41) The diesel oxidation activity of the catalyst prepared in Example 3 was tested in down flow reactor. Typically reaction was carried out in a quartz tubular reactor (inner diameter 4 mm) at atmospheric pressure. Catalyst (0.5 g) was diluted with commercial silica gel of 60-120 mesh (2.0 g) and loaded in the quartz reactor. The reactor was heated with the help of electrically heated furnace. Initially catalyst was heated at 500 C. for 1 h in flow of 10% O.sub.2 in He and then reactor was cooled to 50 C. The reaction was carried out by passing 300 ppm propene+5% O.sub.2+9% H.sub.2O and He gas as a balance. Water was supplied to the reactor by peristaltic pump (Tris ISCO) through a preheated evaporator to generate steam. The total flow of the gases was controlled by mass flow controllers to get desire gas hourly space velocity of 20,000 h.sup.1. The concentrations of the inlet and outlet gases were simultaneously monitored using Micro GC (Agilent 3000 A), fitted with molecular sieves to detect different gases (MS 5 A, for O.sub.2, CO), quadrupole mass spectrometer (Hiden, HPR 20) for CO.sub.2 (44), CO (29), C.sub.3H.sub.6 (41), O.sub.2 (32). The results of the activity are given in FIG. 5. Diesel oxidation activity of catalyst prepared in example 3 showed 100% propene conversion at 300 C. in presence of water.

Example 13

(42) The diesel oxidation activity of the prepared catalyst in Example 3 was tested in down flow reactor. Typically reaction was carried out in a quartz tubular reactor (inner diameter 4 mm) at atmospheric pressure. Catalyst (0.5 g) was diluted with commercial silica gel of 60-120 mesh (2.0 g) and loaded in the quartz reactor. The reactor was heated with the help of electrically heated furnace. Initially catalyst was heated at 500 C. for 1 h in flow of 10% O.sub.2 in He and then reactor was cooled to 50 C. The reaction was carried out by passing 300 ppm propene+5% O.sub.2+10 ppm SO.sub.2 and He gas as a balance. The total flow of the gases was controlled by mass flow controllers to get desire gas hourly space velocity of 20,000 h.sup.1. The concentrations of the inlet and outlet gases were simultaneously monitored using Micro GC (Agilent 3000 A), fitted with molecular sieves to detect different gases (MS 5 A, for O.sub.2, CO), quadrupole mass spectrometer (Hiden, HPR 20) for O.sub.2 (32) CO.sub.2 (44), CO (29), C.sub.3H.sub.6 (41). The results of the activity are given in FIG. 6. Diesel oxidation activity of catalyst prepared in Example 3 showed 100% propene conversion at 250 C. in presence of SO.sub.2.

Example 14

(43) The diesel oxidation activity of the catalyst prepared in Example 3 was tested in down flow reactor. Typically reaction was carried out in a quartz tubular reactor (inner diameter 4 mm) at atmospheric pressure. Catalyst (0.5 g) was diluted with commercial silica gel of 60-120 mesh (2.0 g) and loaded in the quartz reactor. The reactor was heated with the help of electrically heated furnace. Initially, the catalyst was heated at 500 C. for 1 h in flow of 10% O.sub.2 in He and then reactor was cooled to 50 C. The reaction was carried out by passing 300 ppm propene+300 ppm CO+10% O.sub.2+10% CO.sub.2 and He gas as a balance. The total flow of the gases was controlled by mass flow controllers to get desire gas hourly space velocity of 20,000 h.sup.1. The concentrations of the inlet and outlet gases were simultaneously monitored using Micro GC (Agilent 3000 A), fitted with molecular sieves to detect different gases (MS 5 A, for O.sub.2, CO), quadrupole mass spectrometer (Hiden, HPR 20) for CO.sub.2 (44), CO (29), C.sub.3H.sub.6 (41), O.sub.2 (32). The results of the activity are given in FIG. 7. Oxidation activity of catalyst prepared in Example 3 showed 100% propene conversion at 220 C. and 100% CO conversion at 205 C.

Example 15

(44) The diesel oxidation activity of the catalyst prepared in Example 3 was tested in down flow reactor. Typically reaction was carried out in a quartz tubular reactor (inner 15. diameter 4 mm) at atmospheric pressure. Catalyst (0.5 g) was diluted with commercial silica gel of 60-120 mesh (2 g) and loaded in the quartz reactor. The reactor was heated with the help of electrically heated furnace. Initially catalyst was heated at 500 C. for 1 h in flow of 10% O.sub.2 in He and then reactor was cooled to 50 C. The reaction was carried out by passing 1000 ppm CO+5% O.sub.2, and He gas as a balance. The total flow of the gases was controlled by mass flow controllers to get desired gas hourly space velocity of 20,000 h.sup.1. The concentrations of the inlet and outlet gases were simultaneously monitored using Micro GC (Agilent 3000 A), fitted with molecular sieves to detect different gases (MS 5 A, for O.sub.2, CO), quadrupole mass spectrometer (Hiden, HPR 20) for CO.sub.2 (44), CO (29). The results of the activity are given in FIG. 8. Oxidation activity of catalyst prepared in Example 3 showed 100% CO conversion at 125 C.

Example 16

(45) The diesel oxidation activity of the catalyst prepared in Example 5 was tested in down flow reactor. Typically reaction was carried out in a quartz tubular reactor (inner diameter 4 mm) at atmospheric pressure. Catalyst (0.5 g) was diluted with commercial silica gel of 60-120 mesh (2 g) and loaded in the quartz reactor. The reactor was heated with the help of electrically heated furnace. Initially catalyst was heated at 500 C. for 1 h in flow of 10% O.sub.2 in He and then reactor was cooled to 25 C. The reaction was carried out by passing 300 ppm propene+5% O.sub.2, and He gas as a balance. The total flow of the gases was controlled by mass flow controllers to get desired gas hourly space velocity of 20,000 h.sup.1. The concentrations of the inlet and outlet gases were simultaneously monitored using Micro GC (Agilent 3000 A), fitted with molecular sieves to detect different gases (MS 5 A, for O.sub.2, CO), quadrupole mass spectrometer (Hiden, HPR 20) for CO.sub.2 (44), CO (29), C.sub.3H.sub.6 (41). The results of the activity are given in FIG. 9. Diesel oxidation activity of catalyst prepared in Example 5 showed 100% propene conversion at 195 C.

Example 17

(46) The diesel oxidation activity of the catalyst prepared in Example 5 was tested in down flow reactor. Typically reaction was carried out in a quartz tubular reactor (inner diameter 4 mm) at atmospheric pressure. Catalyst (0.5 g) was diluted with commercial silica gel of 60-120 mesh (2.0 g) and loaded in the quartz reactor. The reactor was heated with the help of electrically heated furnace. Initially catalyst was heated at 500 C. for 1 h in flow of 10% O.sub.2 in He and then reactor was cooled to 50 C. The reaction was carried out by passing 300 ppm propene+5% O.sub.2+10 ppm SO.sub.2 and He gas as a balance. The total flow of the gases was controlled by mass flow controllers to get desire gas hourly space velocity of 20,000 h.sup.1. The concentrations of the inlet and outlet gases were simultaneously monitored using Micro GC (Agilent 3000 A), fitted with molecular sieves to detect different gases (MS 5 A, for O.sub.2, CO), quadrupole mass spectrometer (Hiden, HPR 20) for O.sub.2 (32) CO.sub.2 (44), CO (29), SO.sub.2 (64), C.sub.3H.sub.6 (41).

(47) Diesel oxidation activity of catalyst prepared in example 5 showed 100% propene conversion at 200 C. in presence of SO.sub.2. The results of the activity are given in FIG. 10. Diesel oxidation activity of catalyst prepared in example 5 showed 100% propene conversion at 200 C. in presence of SO.sub.2.

Example 18

(48) The diesel oxidation activity of the catalyst prepared in Example 5 was tested in down flow reactor. Typically reaction was carried out in a quartz tubular reactor (inner diameter 4 mm) at atmospheric pressure. Catalyst (0.5 g) was diluted with commercial silica gel of 60-120 mesh (2.0 g) and loaded in the quartz reactor. The reactor was heated with the help of electrically heated furnace. Initially catalyst was heated at 500 C. for 1 h in flow of 10% O.sub.2 in He and then reactor was cooled to 50 C. The reaction was carried out by passing 300 ppm propene+5% O.sub.2+9% H.sub.2O and He gas as a balance. The total flow of the gases was controlled by mass flow controllers to get desire gas hourly space velocity of 20,0001 h.sup.1. The concentrations of the inlet and outlet gases were simultaneously monitored using Micro GC (Agilent 3000 A), fitted with molecular sieves to detect different gases (MS 5 A, for O.sub.2, CO), quadrupole mass spectrometer (Hiden, HPR 20) for O.sub.2 (32) CO.sub.2 (44), CO (29), C.sub.3H.sub.6 (41). The results of the activity are given in FIG. 11. Diesel oxidation activity of catalyst prepared in example 5 showed 100% propene conversion at 325 C. in presence of H.sub.2O.

Example 19

(49) The diesel oxidation activity of the catalyst prepared in Example 5 was tested in down flow reactor. Typically reaction was carried out in a quartz tubular reactor (inner diameter 4 mm) at atmospheric pressure. Catalyst (0.5 g) was diluted with commercial silica gel of 60-120 mesh (2.0 g) and loaded in the quartz reactor. The reactor was heated with the help of electrically heated furnace. Initially catalyst was heated at 500 C. for 1 h in flow of 10% O.sub.2 in He and then reactor was cooled to 50 C. The reaction was carried out by passing 1000 ppm CO+5% O.sub.2 and He gas as a balance. The total flow of the gases was controlled by mass flow controllers to get desire gas hourly space velocity of 20,000 h.sup.1. The concentrations of the inlet and outlet gases were simultaneously monitored using Micro GC (Agilent 3000 A), fitted with molecular sieves to detect different gases (MS 5 A, for O.sub.2, CO), quadrupole mass spectrometer (Hiden, HPR 20) for O.sub.2 (32) CO.sub.2 (44), CO (29). The results of the activity are given in FIG. 12. Diesel oxidation activity of catalyst prepared in example 5 showed 100% CO conversion at 145 C.

Example 20

(50) The diesel oxidation activity of the catalyst prepared in Example 5 was tested in down flow reactor. Typically reaction was carried out in a quartz tubular reactor (inner diameter 4 mm) at atmospheric pressure. Catalyst (0.5 g) was diluted with commercial silica gel of 60-120 mesh (2.0 g) and loaded in the quartz reactor. The reactor was heated with the help of electrically heated furnace. Initially catalyst was heated at 500 C. for 1 h in flow of 10% O.sub.2 in He and then reactor was cooled to 50 C. The reaction was carried out by passing 1000 ppm CO+5% O.sub.2+10 ppm SO.sub.2 and He gas as a balance. The total flow of the gases was controlled by mass flow controllers to get desire gas hourly space velocity of 20,000 h.sup.1. The concentrations of the inlet and outlet gases were simultaneously monitored using Micro GC (Agilent 3000 A), fitted with molecular sieves to detect different gases (MS 5 A, for O.sub.2, CO), quadrupole mass spectrometer (Hiden, HPR 20) for O.sub.2 (32) CO.sub.2 (44), CO (29), SO.sub.2 (64). The results of the activity are given in FIG. 13. Diesel oxidation activity of catalyst prepared in example 5 showed 100% CO conversion at 165 C. in presence of SO.sub.2.

Example 21

(51) The diesel oxidation activity of the catalyst prepared in example 5 was tested in down flow reactor. Typically reaction was carried out in a quartz tubular reactor (inner diameter 4 mm) at atmospheric pressure. Catalyst (0.5 g) was diluted with commercial silica gel of 60-120 mesh (2.0 g) and loaded in the quartz reactor. The reactor was heated with the help of electrically heated furnace. Initially catalyst was heated at 500 C. for 1 h in flow of 10% O.sub.2 in He and then reactor was cooled to 50 C. The reaction was carried out by passing 1000 ppm CO+5% O.sub.2+9% H.sub.2O and He gas as a balance. The total flow of the gases was controlled by mass flow controllers to get desire gas hourly space velocity of 20,000 h.sup.1. The concentrations of the inlet and outlet gases were simultaneously monitored using Micro GC (Agilent 3000 A), fitted with molecular sieves to detect different gases (MS 5 A, for O.sub.2, CO), quadrupole mass spectrometer (Hiden, HPR 20) for O.sub.2 (32) CO.sub.2 (44), CO (29). The results of the activity are given in FIG. 14. Diesel oxidation activity of catalyst prepared in example 5 showed 100% CO conversion at 200 C. in presence of H.sub.2O.

Example 22

(52) The diesel oxidation activity of the catalyst prepared in Example 6 was tested in down flow reactor. Typically reaction was carried out in a quartz tubular reactor (inner diameter 4 mm) at atmospheric pressure. Catalyst (0.5 g) was diluted with commercial silica gel of 60-120 mesh (2.0 g) and loaded in the quartz reactor. The reactor was heated with the help of electrically heated furnace. Initially catalyst was heated at 500 C. for 1 h in flow of 10% O.sub.2 in He and then reactor was cooled to 50 C. The reaction was carried out by passing 1000 ppm CO+5% O.sub.2 and He gas as a balance. The total flow of the gases was controlled by mass flow controllers to get desire gas hourly space velocity of 20,000 The concentrations of the inlet and outlet gases were simultaneously monitored using Micro GC (Agilent 3000 A), fitted with molecular sieves to detect different gases (MS 5 A, for O.sub.2, CO), quadrupole mass spectrometer (Hiden, HPR 20) for O.sub.2 (32) CO.sub.2 (44), CO (29). The results of the activity are given in FIG. 15. Diesel oxidation activity of catalyst prepared in example 6 showed 100% CO conversion at 235 C.

Example 23

(53) The diesel oxidation activity of the catalyst in example 7 catalyst was tested in down flow reactor. Typically reaction was carried out in a quartz tubular reactor (inner diameter 4 mm) at atmospheric pressure. Catalyst (0.5 g) was diluted with commercial silica gel of 60-120 mesh (2.0 g) and loaded in the quartz reactor. The reactor was heated with the help of electrically heated furnace. Initially catalyst was heated at 500 C. for 1 h in flow of 10% O.sub.2 in He and then reactor was cooled to 50 C. The reaction was carried out by passing 1000 ppm CO+5% O.sub.2 and He gas as a balance. The total flow of the gases was controlled by mass flow controllers to get desire gas hourly space velocity of 20,000 h.sup.1. The concentrations of the inlet and outlet gases were simultaneously monitored using Micro GC (Agilent 3000 A), fitted with molecular sieves to detect different gases (MS 5 A, for O.sub.2, CO), quadrupole mass spectrometer (Hiden, HPR 20) for O.sub.2 (32) CO.sub.2 (44), CO (29). The results of the activity are given in FIG. 16. Diesel oxidation activity of catalyst prepared in example 7 showed 100% propene conversion at 200 C.

Advantages of Invention

(54) Non noble-metal based catalyst Easy method of preparation Oxidation activity comparable with that of Pt/Al.sub.2O.sub.3. Lower light off temperature compared to Pt/Al.sub.2O.sub.3 Expected cost will be much cheaper compared to commercial Pt based catalyst (USD 2.2/Kg for Mn). Catalyst shows good sulphur tolerance Catalyst shows good water tolerance