Combined dehydrogenation etherification process

A method of preparing ethers from a feed stream comprising C.sub.4 -C.sub.5 isoalkane hydrocarbons which comprises:

• (a) dehydrogenating said feed stream in a dehydrogenation zone at dehydrogenation conditions including a temperature in the range of 500.degree. C. (930.degree. F.) to 700.degree. C. (1290.degree. F.), a pressure of from 0.1 to 3 bars and in the presence of a dehydrogenation catalyst to produce a dehydrogenation effluent comprising C.sub.4 -C.sub.5 isoolefins and isoalkanes and light gases, said light gases including hydrocarbons having at least as few as 2 carbon atoms per molecule;
• (b) passing C.sub.2 hydrocarbons and essentially all C.sub.3 and higher hydrocarbons in said dehydrogenation effluent to an etherification zone;
• (c) combining C.sub.2 hydrocarbons and essentially all C.sub.3 and higher hydrocarbons and a C.sub.1 -C.sub.5 alcohol in said etherification zone at etherification conditions to obtain essentially complete conversion of said isoolefin and an etherification effluent comprising isoalkanes, alcohol, light gases, and ether;
• (d) separating said etherification effluent into at least a product stream comprising ether, a recycle stream comprising isoalkanes and a light gas stream comprising said light gases in a single fractionation column and recovering said product stream, recycle stream, and light gas stream from said column as a bottoms stream, sidecut stream, and overhead stream, respectively;
• and
• (e) returning at least a portion of said recycle stream to said dehydrogenation unit.

A method for preparing ethers from a feed stream comprising isobutane which comprises:

• (a) combining said feed stream with a hydrogen stream and an isobutane recycle stream to obtain a combined feed stream;
• (b) passing said combined feed stream to a dehydrogenation zone and dehydrogenating said combined feed stream in said dehydrogenation zone at dehydrogenation conditions including a temperature in the range of 500.degree. C. (930.degree. F.) to 700.degree. C. (1290.degree. F.), a pressure of from 0.1 to 3 bars and in the presence of a dehydrogenation catalyst to obtain a dehydrogenation effluent comprising isobutene, isobutane, and light gases, said light gases including hydrocarbons having at least as few as 2 carbon atoms per molecule;
• (c) removing hydrogen from said dehydrogenation zone effluent and recovering at least a portion of said hydrogen in said hydrogen stream;
• (d) passing essentially all C.sub.2 and higher hydrocarbons in said dehydrogenation effluent to an etherification zone;
• (e) combining said essentially all C.sub.2 and higher hydrocarbons and a C.sub.1 -C.sub.5 alcohol in said etherification zone at etherification conditions including a temperature of 50.degree. C. (120.degree. F.) to 80.degree. C. (175.degree. F.), a pressure of 10 bars to 15 bars and in the presence of an etherification catalyst to obtain essentialy complete conversion of isobutene and produce an etherification effluent stream comprising a tertiary butyl ether, isobutane, alcohol, and light gases having less than 4 carbon atoms per molecule;
• and
• (f) separating said etherification effluent into at least a product stream comprising ether, said isobutane recycle stream, and a light gas stream comprising said light gases in a single fractionation column and recovering said product stream, recycle stream, and light gas stream from said column as a bottoms stream, sidecut stream, and overhead stream, respectively.