Process for the manufacture of methyl t-butyl ether

A process for the manufacture of methyl t-butyl ether which process comprises the following steps:

• (i) cracking a hydrocarbon feedstock in a hydrocarbon cracker to give an ethylene-rich stream;
• (ii) separating a C.sub.4 -hydrocarbon stream into an isobutane enriched stream and an n-butane enriched stream in a de-isobutanizer unit, isomerizing the n-butane enriched stream in a catalytic isomerization reactor to give an isobutane/n-butane mixture, and recycling the isobutane/n-butane mixture to the deisobutanizer unit;
• (iii) reacting a mixture comprising the ethylene-rich stream from step (i) and the isobutane enriched stream from step (ii) over a chromium oxide on alumina transhydrogenation catalyst at a temperature in the range from 400.degree. to 550.degree. C. and at a pressure in the range of from 1.0 to 10 atmospheres to give a hydrocarbon mixture comprising isobutene and ethane;
• (iv) separating the hydrocarbon mixture from step (iii) into a C.sub.4 -hydrocarbon enriched stream comprising isobutene and a C.sub.2 -hydrocarbon enriched stream comprising ethane in a debutanizer column and reacting said C.sub.4 -hydrocarbon enriched stream with methanol in the liquid phase over an acidic solid phase catalyst to give methyl t-butyl ether and a residual C.sub.4 -hydrocarbon stream;
• and
• (v) recycling the C.sub.2 -hydrocarbon enriched stream to the hydrocarbon cracker, collecting the methyl t-butyl ether, and recycling the residual C.sub.4 -hydrocarbon stream to the C.sub.4 -hydrocarbon stream.

A process for the manufacture of methyl t-butyl ether which process comprises the following steps:

• (i) cracking a hydrocarbon feedstock in hydrocarbon cracker to give an ethylene-rich stream;
• p1 (ii) separating a C.sub.4 -hydrocarbon stream into an isobutane enriched stream and an n-butane enriched stream in a deisobutanizer unit and recycling the n-butane enriched stream to the hydrocarbon cracker for use as feedstock;
• (iii) reacting a mixture comprising the ethylene-rich stream from step (i) and the isobutane enriched stream from step (ii) over a chromium oxide on alumina transhydrogenation catalyst at a temperature in the range from 400.degree. to 550.degree. C. and at a pressure in the range of from 1.0 to 10 atmospheres to give a hydrocarbon mixture comprising isobutene and ethane;
• (iv) separating the hydrocarbon mixture from step (iii) into a C.sub.4 -hydrocarbon enriched stream comprising isobutene and a C.sub.2 -hydrocarbon enriched stream comprising ethane in a debutanizer column and reacting said C.sub.4 -hydrocarbon enriched stream with methanol in the liquid phase over an acidic solid phase catalyst to give methyl t-butyl ether and a residual C.sub.4 -hydrocarbon stream;
• and
• (v) recycling the C.sub.2 -hydrocarbon enriched stream to the hydrocarbon cracker, collecting the methyl t-butyl ether, and recycling the residual C.sub.4 -hydrocarbon stream to the C.sub.4 -hydrocarbon stream.

A process for the manufacture of methyl t-butyl ether which process comprises the following steps:

• (i) separating hydrogen from a refinery dry gas stream obtained from a refinery hydrocarbon cracking process to give an ethylene enriched stream and recycling the hydrogen for refinery use;
• (ii) separating a C.sub.4 -hydrocarbon stream obtained from natural gas or refinery operations into an isobutane enriched stream and an n-butane enriched stream in a deisobutanizer unit and recycling the n-butane enriched stream for refinery use;
• (iii) reacting a mixture comprising the ethylene enriched stream from step (i) and the isobutane enriched stream from step (ii) over a chromium oxide on alumina transhydrogenation catalyst at a temperature in the range from 400.degree. to 550.degree. C. and at a pressure in the range from 1.0 to 10 atmospheres to give a hydrocarbon mixture comprising isobutene and ethane;
• (iv) separating the hydrocarbon mixture from step (iii) into a C.sub.4 -hydrocarbon enriched stream comprising isobutene and a C.sub.2 -hydrocarbon enriched stream comprising ethane in a debutanizer column and reacting said C.sub.4 -hydrocarbon enriched stream with methanol in the liquid phase over an acidic solid phase catalyst to give methyl t-butyl ether and a residual C.sub.4 -hydrocarbon stream;
• and
• (v) collecting the methyl t-butyl ether and recycling the C.sub.2 -hydrocarbon enriched stream and the residual C.sub.4 -hydrocarbon stream for refinery use.