Production of propylene via simultaneous dehydration and skeletal isomerisation of isobutanol on acid catalysts followed by metathesis

A process for the production of propylene in which in a first step isobutanol is subjected to a simultaneous dehydration and skeletal isomerisation to make corresponding olefins, having the same number of carbons and comprising a mixture of n-butenes and iso-butene and in a second step n-butenes are subjected to methathesis, said process comprising:

• a) introducing in a dehydration and isomerization reactor a stream (A) comprising isobutanol, wherein the isobutanol is present in the stream (A) in an amount ranging from 30 to 100 weight percent based on a total weight of the stream (A),
• b) contacting said stream (A) with a dehydration and isomerization catalyst in said dehydration and isomerization reactor at conditions effective to dehydrate at least a portion of the isobutanol and skeletal isomerase an iso-butyl moiety of at least a portion of the isobutanol to make a mixture of n-butenes and iso-butene, wherein the dehydration and isomerization catalyst is a crystalline silicate;
• a dealuminated crystalline silicate;
• a phosphorus modified crystalline silicate;
• a silicoaluminaphosphate molecular sieve;
• or a silicated, zirconated, titanated, or fluorinated alumina,
• c) recovering from said dehydration and isomerization reactor a stream (B) comprising the mixture of n-butenes and iso-butene,
• d) fractionating said mixture of n-butenes and iso-butene to produce an n-butenes stream (N) and to remove at least part of the isobutene,
• e) sending the n-butenes stream (N) to a methathesis reactor and contacting the n-butenes stream (N) with a metathesis catalyst in said methathesis reactor, at conditions effective to produce propylene,
• f) recovering from said methathesis reactor a stream (P) comprising propylene, unreacted n-butenes, and heavies,
• g) fractionating the stream (P) to recover propylene.