Autothermal process for the production of olefins

Abstract

A process and catalyst for the partial oxidation of paraffinic hydrocarbons, such as ethane, propane, naphtha, and natural gas condensates, to olefins, such as ethylene and propylene. The process involves contacting a paraffinic hydrocarbon with oxygen in the presence of a catalyst under autothermal process conditions. The catalyst comprises a Group 8B metal and, optionally, a promoter metal, such as tin or copper, supported on a fiber monolith support, preferably a ceramic fiber mat monolith. In another aspect, the invention is a process of oxidizing a paraffinic hydrocarbon to an olefin under autothermal conditions in the presence of a catalyst comprising a Group 8B metal and, optionally, a promoter metal, the metals being loaded onto the front face of a monolith support. An on-line method of synthesizing and regenerating catalysts for autothermal oxidation processes is also disclosed. This divisional case covers the catalyst composition and the method of preparing an olefin using the catalyst.

What is claimed is:  
     
         1 . A process of preparing an olefin comprising contacting a paraffinic hydrocarbon with oxygen in the presence of a catalyst, the contacting being conducted under autothermal process conditions sufficient to prepare the olefin, the catalyst comprising at least one Group 8B metal and, optionally, at least one promoter metal, said metal(s) being supported on a fiber monolith support.  
     
     
         2 . The process of  claim 1  wherein the paraffinic hydrocarbon comprises one or more saturated hydrocarbons each having from 2 to about 25 carbon atoms.  
     
     
         3 . The process of  claim 2  wherein the paraffinic hydrocarbon comprises ethane, propane, or mixtures thereof.  
     
     
         4 . The process of  claim 2  wherein the paraffinic hydrocarbon is selected from naphtha, natural gas condensates, gas oils, vacuum gas oils, and mixtures thereof.  
     
     
         5 . The process of  claim 1  wherein the molar ratio of paraffinic hydrocarbon to oxygen ranges from about 3 to about 13 times the stoichiometric ratio of hydrocarbon to oxygen for complete combustion to carbon dioxide and water.  
     
     
         6 . The process of  claim 1  wherein the molar ratio of paraffinic hydrocarbon to oxygen is greater than about 0.1:1 and less than about 3.0:1.  
     
     
         7 . The process of  claim 1  wherein a diluent is used.  
     
     
         8 . The process of  claim 7  wherein the diluent is used in an amount greater than about 0.1 mole percent and less than about 70 mole percent, based on the total reactant feed.  
     
     
         9 . The process of  claim 1  wherein the Group 8B metal is a platinum group metal.  
     
     
         10 . The process of  claim 9  wherein the platinum group metal is platinum.  
     
     
         11 . The process of  claim 1  wherein the support is a ceramic selected from silica, alumina, silica-aluminas, aluminosilicates, zirconia, titania, boria, zirconia mullite alumina, lithium aluminum silicates, and oxide-bonded silicon carbide.  
     
     
         12 . The process of  claim 11  wherein the ceramic support comprises from about 60 to about 100 weight percent alumina.  
     
     
         13 . The process of  claim 1  wherein each fiber comprising the fiber monolith has a diameter greater than about 1 micron and less than about 20 microns, and a surface area greater than about 0.001 m 2 /g and less than about 1 m 2 /g.  
     
     
         14 . The process of  claim 1  wherein the fiber monolith is in the form of a fiber mat.  
     
     
         15 . The process of  claim 1  wherein the promoter metal is selected from Groups 2A, 1B, 3A, 4A, and the rare earth lanthanide elements, and mixtures thereof.  
     
     
         16 . The process of  claim 15  wherein the atomic ratio of Group 8B metal to promoter metal ranges from greater than about 1:10 to less than about 1:0.5.  
     
     
         17 . The process of  claim 1  wherein the temperature is greater than about 750° C. and less than about 1,150° C.  
     
     
         18 . The process of  claim 1  wherein the pressure ranges from about 1 atm abs (100 kPa abs) to about 20 atm abs (2,000 kPa abs).  
     
     
         19 . The process of  claim 1  wherein the gas hourly space velocity is greater than about 80,000 h −1  and less than about 6,000,000 h −1 .  
     
     
         20 . The process of  claim 1  wherein the conversion of paraffinic hydrocarbon is greater than about 55 mole percent.  
     
     
         21 . The process of  claim 1  wherein the olefin selectivity is greater than about 70 carbon atom percent.  
     
     
         22 . The process of  claim 1  wherein the paraffin is ethane and the contacting is conducted under autothermal conditions at an ethane to oxygen molar ratio greater than about 1.5:1 and less than about 2.7:1, a gas hourly space velocity greater than about 100,000 h −1  and less than about 4,000,000 h −1 , wherein a diluent is used in an amount greater than about 1 mole percent and less than about 70 mole percent based on the total reactant feed, wherein the Group 8B metal is platinum, and the fiber monolith comprises from about 60 to about 100 weight percent alumina.  
     
     
         23 . A catalyst composition comprising at least one Group 8B metal and at least one promoter metal, said metals being supported on a fiber monolith support.  
     
     
         24 . The composition of  claim 23  wherein the Group 8B metal is a platinum group metal.  
     
     
         25 . The composition of  claim 24  wherein the platinum group metal is platinum.  
     
     
         26 . The composition of  claim 23  wherein the promoter metal is selected from Groups 2A, 1B, 3A, 4A, and the lanthanide elements, and mixtures thereof.  
     
     
         27 . The composition of  claim 23  wherein the monolith is a ceramic selected from silica, alumina, silica-aluminas, aluminosilicates, zirconia, titania, boria, zirconia mullite alumina, lithium aluminum silicates, and oxide-bonded silicon carbide.  
     
     
         28 . The composition of  claim 27  wherein the ceramic monolith comprises from about 60 to about 100 weight percent alumina.  
     
     
         29 . The composition of  claim 23  wherein each of the fibers comprising the fiber monolith has a fiber diameter greater than about 1 micron and less than about 20 microns, and a surface area greater than about 0.001 m 2 /g and less than about 1 m 2 /g.  
     
     
         30 . The composition of  claim 23  wherein the fiber monolith consists essentially of 62 weight percent alumina, 24 weight percent silica, and 14 weight percent boria.  
     
     
         31 . A catalyst composition comprising at least one Group 8B metal and, optionally, at least one promoter metal, said metal(s) being supported on the front face of a monolith support.  
     
     
         32 . The composition of  claim 31  wherein the Group 8B metal is a platinum group metal.  
     
     
         33 . The composition of  claim 32  wherein the platinum group metal is platinum.  
     
     
         34 . The composition of  claim 31  wherein the promoter metal is selected from Groups 2A, 1B, 3A, 4A, and the lanthanide elements, and mixtures thereof.  
     
     
         35 . The composition of  claim 31  wherein the monolith is a ceramic selected from silica, alumina, silica-aluminas, aluminosilicates, zirconia, titania, boria, zirconia mullite alumina, lithium aluminum silicates, and oxide-bonded silicon carbide.  
     
     
         36 . The composition of  claim 31  wherein the ceramic monolith comprises from about 60 to about 100 weight percent alumina.  
     
     
         37 . The composition of  claim 31  wherein the monolith support is in the form of a honeycomb, foam, or fiber mat.  
     
     
         38 . A process of preparing an olefin comprising contacting a paraffinic hydrocarbon with oxygen in the presence of a catalyst, the contacting being conducted under autothermal process conditions sufficient to prepare the olefin, the catalyst comprising at least one Group 8B metal and, optionally, at least one promoter metal, said metal(s) being supported on the front face of a monolith support.  
     
     
         39 . The process of  claim 38  wherein the paraffinic hydrocarbon comprises one or more saturated hydrocarbons each having from 2 to about 25 carbon atoms.  
     
     
         40 . The process of  claim 38  wherein the paraffinic hydrocarbon comprises ethane, propane, or mixtures thereof.  
     
     
         41 . The process of  claim 38  wherein the paraffinic hydrocarbon is selected from naphtha, natural gas condensates, gas oils, vacuum gas oils, and mixtures thereof.  
     
     
         42 . The process of  claim 38  wherein the molar ratio of paraffinic hydrocarbon to oxygen ranges from about 3 to about 13 times the stoichiometric ratio of hydrocarbon to oxygen for complete combustion to carbon dioxide and water.  
     
     
         43 . The process of  claim 38  wherein the molar ratio of paraffinic hydrocarbon to oxygen is greater than about 0.1:1 and less than about 3.0:1.  
     
     
         44 . The process of  claim 38  wherein a diluent is used.  
     
     
         45 . The process of  claim 44  wherein the diluent is used in an amount greater than about 0.1 mole percent and less than about 70 mole percent, based on the total reactant feed.  
     
     
         46 . The process of  claim 38  wherein the Group 8B metal is a platinum group metal.  
     
     
         47 . The process of  claim 46  wherein the platinum group metal is platinum.  
     
     
         48 . The process of  claim 38  wherein the support is a ceramic selected from silica, alumina, silica-aluminas, aluminosilicates, zirconia, titania, boria, zirconia mullite alumina, lithium aluminum silicates, and oxide-bonded silicon carbide.  
     
     
         49 . The process of  claim 48  wherein the ceramic support comprises from about 60 to about 100 weight percent alumina.  
     
     
         50 . The process of  claim 38  wherein the promoter metal is selected from Groups 2A, 1B, 3A, 4A, and the rare earth lanthanide elements, and mixtures thereof.  
     
     
         51 . The process of  claim 38  wherein the atomic ratio of Group 8B metal to promoter metal ranges from greater than about 1:10 to less than about 1:0.5.  
     
     
         52 . The process of  claim 38  wherein the temperature is greater than about 750° C. and less than about 1,150° C.  
     
     
         53 . The process of  claim 38  wherein the pressure ranges from about 1 atm abs (100 kPa abs) to about 20 atm abs (2,000 kPa abs).  
     
     
         54 . The process of  claim 38  wherein the gas hourly space velocity is greater than about 80,000 h −1  and less than about 6,000,000 h −1 .  
     
     
         55 . The process of  claim 38  wherein the conversion of paraffinic hydrocarbon is greater than about 55 mole percent.  
     
     
         56 . The process of  claim 38  wherein the olefin selectivity is greater than about 70 carbon atom percent.  
     
     
         57 . The process of  claim 38  wherein the paraffin is ethane and the contacting is conducted under autothermal conditions at an ethane to oxygen molar ratio greater than about 1.5:1 and less than about 2.7:1, a gas hourly space velocity greater than about 100,000 h −1  and less than about 4,000,000 h −1 , wherein a diluent is used in an amount greater than about 1 mole percent and less than about 70 mole percent based on the total reactant feed, wherein the Group 8B metal is platinum, and the monolith comprises from about 60 to about 100 weight percent alumina.