Process for preparing an alkene

A process for the preparation of an alkene from an oxygenate, the process comprising contacting a reactant feedstream comprising at least one oxygenate reactant and water with a supported heteropolyacid catalyst at a temperature of at least 170° C., wherein the process is initiated using a start-up procedure comprising the following steps:

• (i) heating the supported heteropolyacid catalyst to a temperature of at least 220° C.;
• (ii) maintaining the heat-treated supported heteropolyacid catalyst of step (i) at a temperature of at least 220° C. for a time sufficient to remove chemically bound water from the heteropolyacid component of the supported heteropolyacid catalyst;
• (iii) under an anhydrous atmosphere, reducing the temperature of the heat-treated supported heteropolyacid catalyst of step (ii) to a temperature below 220° C.;
• and
• (iv) contacting the supported heteropolyacid catalyst of step (iii) with the reactant feedstream at a temperature of at least 170° C.

A process for the preparation of an alkene from an oxygenate, the process comprising contacting a reactant feedstream comprising at least one oxygenate reactant and water with a supported heteropolyacid catalyst at a temperature of at least 170° C., wherein the process is initiated using a start-up procedure comprising the following steps:

• (i) heating the supported heteropolyacid catalyst to a temperature of at least 220° C.;
• (ii) maintaining the heat-treated supported heteropolyacid catalyst of step (i) at a temperature of at least 220° C. for a time sufficient to remove chemically bound water from the heteropolyacid component of the supported heteropolyacid catalyst;
• (iii) under an anhydrous atmosphere, reducing the temperature of the heat-treated supported heteropolyacid catalyst of step (ii) to a temperature below 220° C.;
• (iv) contacting the supported heteropolyacid catalyst of step (iii) with a reactant feed comprising the oxygenate component of the reactant feedstream and no water at a temperature of at least 170° C.;
• and
• (v) whilst maintaining a temperature of at least 170° C., adding water to the reactant feed of step (iv) to form the reactant feedstream.