Patent ID: 6228798
Filing Date: 2001-05-08
Classification: B01J,C07C

Abstract:
A method of making a vanadium phosphorus oxide (VPO) catalyst, the method comprising the steps of:precipitating, from a solution comprising dissolved V.sup.4+ ions and V.sup.5+ ions at a total concentration of 45-65 g/l, a vanadium-containing and phosphorus-containing precipitate comprising a complex in accordance with the formula VOHPO.sub.4.1/2H.sub.2 O; andcalcining the precipitate under an inert atmosphere, to produce a VPO catalyst having an active phase in accordance with the formula (VO).sub.2 P.sub.2 O.sub.9, the solution from which the precipitate is precipitated comprising dissolved cations of at least two dopant metals selected from the group of metals consisting of Bi, Zr, Cr, Ce, Co, Mn, Mg and Mo, said dissolved dopant metal cations being present in the solution in proportions such that the precipitate comprises 1-25% by mass of dopant metal cations in total, the balance being the VOHPO.sub.4.1/2H.sub.2 O complex, each dopant metal forming 0.1-20% by mass of the precipitate, the dopant metal cations being present in the solution as a mixture of cations of different dopant metals, wherein, if said mixture of cations consist of cations of three different dopant metals, the three different dopant metals are selected from the group consisting of:Bi and Zr and Cr;Bi and Zr and Ce;Bi and Zr and Co;Bi and Zr and Mn;Bi and Zr and Mg;Bi and Zr and Mo;Bi and Cr and Ce;Bi and Cr and Co;Bi and Cr and Mn;Bi and Cr and Mg;Bi and Cr and Mo;Bi and Ce and Co;Bi and Ce and Mn;Bi and Ce and Mg;Bi and Ce and Mo;Bi and Co and Mn;Bi and Co and Mg;Bi and Co and Mo;Bi and Mn and Mg;Bi and Mn and Mo;Bi and Mg and Mo;Zr and Cr and Ce;Zr and Cr and Mn;Zr and Cr and Mg;Zr and Cr and Mo;Zr and Ce and Co;Zr and Ce and Mn;Zr and Ce and Mg;Zr and Ce and Mo;Zr and Co and Mn;Zr and Co and Mg;Zr and Co and Mo;Zr and Mn and Mg;Zr and Mn and Mo;Zr and Mg and Mo;Cr and Ce and Co;Cr and Ce and Mn;Cr and Ce and Mg;Cr and Ce and Mo;Cr and Co and Mn;Cr and Co and Mg;Cr and Co and Mo;Cr and Mn and Mg;Cr and Mn and Mo;Cr and Mg and Mo;Ce and Co and Mn;Ce and Co and Mg;Ce and Co and Mo;Ce and Mn and Mg;Ce and Mn and Mo;Ce and Mg and Mo;Co and Mn and Mo;Co and Mg and Mo; andMn and Mg and Mo,and wherein, if said mixture of cations consists of cations of two different dopant metals, the two different dopant metals are selected from the group consisting of:Bi and Zr;Bi and Cr;Bi and Ce;Bi and Co;Bi and Mn;Bi and Mg;Bi and Mo;Zr and Ce;Zr and Mn;Zr and Mg;Zr and Mo;Cr and Ce;Cr and Mn;Cr and Mg;Cr and Mo;Ce and Co;Ce and Mn;Ce and Mg;Ce and Mo;Co and Mo;Mn and Mo; andMg and Mo.