Patent ID: 7049466
Filing Date: 2006-05-23
Classification: B01J,C07C,Y02P

Abstract:
1. A method for producing an unsaturated carboxylic acid comprises: (a) contacting, in a reaction zone, an alkane with a catalyst containing a mixed metal oxide, under conditions which produce a product gas comprising said unsaturated carboxylic acid, unreacted alkane and a product alkene; (b) recovering unreacted alkane and product alkene from said product gas; and (c) recycling said recovered unreacted alkane and product alkene to said reaction zone, said reaction zone comprising at least two sub-zones which are disposed sequentially relative to one another, wherein said alkane passes through said sub-zones in sequential order; wherein each of said at least two sub-zones contains said catalyst which contains said mixed metal oxide which consists of a material having the formula wherein A is at least one element selected from the group consisting of molybdenum and tungsten, wherein M is at least one element selected from the group consisting of vanadium, cerium and chromium, wherein N is at least one element selected from the group consisting of tellurium, bismuth and selenium, wherein X is at least one element selected from the group consisting of niobium, tantalum, titanium, aluminum, zirconium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, platinum, bismuth, boron, indium, arsenic, germanium, tin, lithium, sodium, potassium, rubidium, cesium, francium, beryllium, magnesium, calcium, strontium, barium, hafnium, lead, phosphorus, promethium, europium, gadolinium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, gold, silver, palladium, gallium, zinc, praseodymium, rhenium, iridium, neodymium, yttrium, samarium and terbium, wherein 0.25<a<0.98, 0.003<m<0.5, 0.003<n<0.5, 0.003<x<0.5 and o is dependent on the oxidation state of the other elements, and wherein said catalyst in each of said at least two sub-zones has the same composition and catalyzes the conversion of said alkane to said unsaturated carboxylic acid.