Novel crystalline silicas and their use as alkylation catalysts, e.g., methylation of toluene. The performance of the catalysts can be improved by selected promoters.

Crystalline silica and use in alkylation of aromatics

Catalysts for the oxidation of hydrocarbons to acid anhydrides, for example maleic and phthalic anhydrides, are prepared from a vanadium/phosphorus mixed oxide precursor by conditioning it by contact with a strong acid of concentration at least 3N and solvent extraction to remove unwanted phases. The treated precursor is converted to a catalytically active form by heating. Novel catalysts containing phase X are produced. The catalysts may contain rare earth metal promoters.

Production of maleic anhydride

The invention relates to a vanadium-, phosphorus- and oxygen-containing catalyst that is used for producing maleic anhydride by heterogeneous catalytic gas phase oxidation of a hydrocarbon carrying at least four carbon atoms in which the ratio of phosphorus/vanadium is 0.9 to 1.5. Said catalyst comprises particles with an average diameter of at least 2 mm and the composition has a x-ray powder diffraction pattern, obtained by irradiation with CuKα radiation (μ = 1.54 . 10-10 m), that produces in the 2υ range of 10° to 70° a signal/noise ratio of ≤ 10 for all diffraction lines that can be attributed to a vanadium- and phosphorus-containing phase. The invention further relates to a method for producing such a catalyst and to a method for producing maleic anhydride on such a catalyst.

Catalyst and method for producing maleic anhydride

The present invention provides improved oxidation catalysts containing mixed oxides of vanadium and phosphorus and the method for the preparation thereof, which catalysts are particularly effective in the oxidation of n-butane, n-butenes, 1,3-butadiene or a mixture thereof with molecular oxygen or an oxygen-containing gas in the vapor phase to produce excellent yields of maleic anhydride with very good selectivity. At least one vanadium compound, a substantial portion of which is in the pentavalent state, and at least one phosphorus-containing compound is added to an organic liquid medium capable of reducing at least a portion of the vanadium to a +4 valence state, to form a reaction mixture. Partial reduction of the vanadium is effected in the presence of the phosphorus-containing compound and a highly ordered and uniform mixed vanadium phosphorus oxide-containing catalyst precursor is formed.

Preparation of maleic anhydride

The prior art discloses that phosphorus-vanadium-oxygen catalysts wherein the phosphorus to vanadium atom ratio is between about 1:2 and about 2:1, and wherein at least about 20 atom percent of the vanadium is in the tetravalent state, are useful for the conversion of aliphatic hydrocarbons to maleic anhydride. It has now been found that when the pore volume of the catalysts from pores having diameters between about 0.8 micron and about 10 microns is greater than 0.02 cc/g, the catalyst is particularly useful for the conversion of saturated hydrocarbons, such as butane, to maleic anhydride.

Phosphorus-vanadium-oxygen catalysts having a specific pore volume

A high-activity vanadium-phosphorus mixed-oxide catalyst is prepared by a method requiring heating the catalyst precursor at about 350°-410°C. to drive off at least a portion of the water of hydration, and then at a higher temperature. The catalyst is especially useful for oxidation of n-butane to maleic anhydride.

Vanadium-phosphorus oxide oxidation of N-butane to maleic anhydride

A process for producing maleic anhydride which comprises partially oxidizing a hydrocarbon feed at a temperature in the range 300°-600° C by contacting said feed and an oxygen-containing gas with a catalyst comprising vanadium, phosphorus and silicon oxides prepared by steps comprising coprecipitating vanadium oxide and silica or a silica precursor. Preferably an organic silicon compound, especially an alkyl orthosilicate, is used to form the silica precipitate. Preferably the organic silicon compound is added so as to coprecipitate both during the reduction of the vanadium from a +5 oxidation state to a 3.5-4.6 oxidation state and also is added or is present so as to precipitate silica or a silica precursor simultaneously with the reaction of phosphoric acid with the reduced vanadium.

Producing maleic anhydride using certain phosphorous-vanadium-silicon-oxygen containing catalysts

A method is described for the preparation and use of an improved vanadium-phosphorus mixed oxide oxidation catalyst and of a novel mixed oxide monohydrate which is a precursor of the catalyst.

Vanadium-phosphorus mixed oxide oxidation catalysts

Catalyst for producing maleic anhydride

A process for the preparation of calcium fluoride from industrial waste waters which comprises treatment of the waste waters with potassium hydroxide, followed by lime precipitation, neutralization with carbon dioxide and filtration to provide the calcium fluoride product.

Jonas P. Harrison

Papers

Vanadium-phosphorus oxide oxidation of N-butane to maleic anhydride

Producing maleic anhydride using certain phosphorous-vanadium-silicon-oxygen containing catalysts

Vanadium-phosphorus mixed oxide oxidation catalysts

Catalyst for producing maleic anhydride

Process for calcium fluoride production from industrial waste waters