Embodiments of methods of synthesizing a metathesis catalyst system, which include impregnating tungsten oxide on silica support in the presence of a precursor to produce a base catalyst; calcining the base catalyst; impregnating a metal oxide co-catalyst comprising a metal oxide onto the surface of the base catalyst to produce a doped catalyst; and calcining the doped catalyst to produce a metathesis catalyst system. Further embodiments of processes for the production of propylene, which include contacting a hydrocarbon feedstock comprising a mixture of 1-butene and 2-butene with embodiments of the metathesis catalyst system to produce, via metathesis conversion, a product stream comprising propylene.

Embodiments of methods of synthesizing a metathesis catalyst system, which include impregnating tungsten oxide on silica support in the presence of a precursor to produce a base catalyst; calcining the base catalyst; impregnating a metal oxide co-catalyst comprising a metal oxide onto the surface of the base catalyst to produce a doped catalyst; and calcining the doped catalyst to produce a metathesis catalyst system. Further embodiments of processes for the production of propylene, which include contacting a hydrocarbon feedstock comprising a mixture of 1-butene and 2-butene with embodiments of the metathesis catalyst system to produce, via metathesis conversion, a product stream comprising propylene.

Embodiments of methods of synthesizing a metathesis catalyst system, which include impregnating tungsten oxide on silica support in the presence of a precursor to produce a base catalyst; calcining the base catalyst; dispersing a solid metal-based co-catalyst onto the surface of the base catalyst to produce a doped catalyst; and calcining the doped catalyst to produce a metathesis catalyst system. Further embodiments of processes for the production of propylene, which include contacting a hydrocarbon feedstock comprising a mixture of 1-butene and 2-butene with embodiments of the metathesis catalyst system to produce, via metathesis conversion, a product stream comprising propylene.

Embodiments of methods of synthesizing a metathesis catalyst system, which include impregnating tungsten oxide on silica support in the presence of a precursor to produce a base catalyst; calcining the base catalyst; dispersing a solid metal-based co-catalyst onto the surface of the base catalyst to produce a doped catalyst; and calcining the doped catalyst to produce a metathesis catalyst system. Further embodiments of processes for the production of propylene, which include contacting a hydrocarbon feedstock comprising a mixture of 1-butene and 2-butene with embodiments of the metathesis catalyst system to produce, via metathesis conversion, a product stream comprising propylene.

A process for preparing a catalyst material, includes: (a) providing a support material having surface hydroxyl (OH) groups, the support material is ceria (CeO.sub.2), zirconia (ZrO.sub.2) or a combination, and the support material contains between 0.3 and 2.0 mmol OH groups/g of the support material; (b) reacting the support material with at least one of: (b1) a compound containing at least one alkoxy or phenoxy group bound though its oxygen atom to a metal element from Group 5 (V, Nb, Ta) or Group 6 (Cr, Mo, W); (b2) a compound containing at least one hydrocarbon group bound though a carbon atom to a metal element from Group 5 or 6; (b3) a compound containing at least one hydrocarbon group bound though a carbon atom to a metal element which is copper (Cu); and (c) calcining the product obtained in step (b).

A process for preparing a catalyst material, includes: (a) providing a support material having surface hydroxyl (OH) groups, the support material is ceria (CeO.sub.2), zirconia (ZrO.sub.2) or a combination, and the support material contains between 0.3 and 2.0 mmol OH groups/g of the support material; (b) reacting the support material with at least one of: (b1) a compound containing at least one alkoxy or phenoxy group bound though its oxygen atom to a metal element from Group 5 (V, Nb, Ta) or Group 6 (Cr, Mo, W); (b2) a compound containing at least one hydrocarbon group bound though a carbon atom to a metal element from Group 5 or 6; (b3) a compound containing at least one hydrocarbon group bound though a carbon atom to a metal element which is copper (Cu); and (c) calcining the product obtained in step (b).

A process for preparing a catalyst material, includes the steps of: (a) providing a support material having surface hydroxyl (OH) groups, wherein the support material is ceria (CeO.sub.2), zirconia (ZrO.sub.2) or a combination of thereof; (b) reacting the support material having surface hydroxyl (OH) groups of step (a) with a precursor containing two transition metal atoms, each chosen independently from the group consisting of: W, Mo, Cr, Ta, Nb, V, Mn; (c) calcining the product obtained in step (b) in order to provide a catalyst material showing dual site surface species containing pairs of transition metal atoms derived from the precursor that are present in oxide form on the support material. Additionally, a catalyst material is obtained by the process set out above, and the catalyst material is used as an ammonia selective catalytic reduction (NH.sub.3-SCR) catalyst for nitrogen oxides (NOx) reduction.

A process for preparing a catalyst material, includes the steps of: (a) providing a support material having surface hydroxyl (OH) groups, wherein the support material is ceria (CeO.sub.2), zirconia (ZrO.sub.2) or a combination of thereof; (b) reacting the support material having surface hydroxyl (OH) groups of step (a) with a precursor containing two transition metal atoms, each chosen independently from the group consisting of: W, Mo, Cr, Ta, Nb, V, Mn; (c) calcining the product obtained in step (b) in order to provide a catalyst material showing dual site surface species containing pairs of transition metal atoms derived from the precursor that are present in oxide form on the support material. Additionally, a catalyst material is obtained by the process set out above, and the catalyst material is used as an ammonia selective catalytic reduction (NH.sub.3-SCR) catalyst for nitrogen oxides (NOx) reduction.

The invention provides a shut down method for a process for the preparation of glycols from a starting material comprising one or more saccharides in the presence 5 of hydrogen and a catalyst system comprising one or more retro-aldol catalysts comprising tungsten and one or more catalytic species suitable for hydrogenation in a reactor, said method comprising removing the one or more retro-aldol catalysts from the reactor whilst also in the presence of one or more agents suitable to suppress tungsten precipitation.

The invention provides a shut down method for a process for the preparation of glycols from a starting material comprising one or more saccharides in the presence 5 of hydrogen and a catalyst system comprising one or more retro-aldol catalysts comprising tungsten and one or more catalytic species suitable for hydrogenation in a reactor, said method comprising removing the one or more retro-aldol catalysts from the reactor whilst also in the presence of one or more agents suitable to suppress tungsten precipitation.