Preparation method of oxyvanadium phosphate catalyst and application thereof in catalytic oxidation reaction

Abstract

The invention discloses a preparation method of an oxyvanadium phosphate catalyst. The preparation method disclosed by the invention comprises the following steps: carrying out material synthesis reaction on phosphorus sources such as sodium hypophosphite and ammonium hypophosphite and one or more vanadium sources in vanadium pentoxide and ammonium metavanadate in multiple kinds of ionic liquid and eutectic mixtures, using assisted microwave heating means in the reaction process, preparing to obtain an oxyvanadium phosphate precursor VOHPO4.1 / 2H2O, and calcining the oxyvanadium phosphate precursor in air containing 1.5% of butane, thereby obtaining the final catalyst oxyvanadium phosphate. The ionic liquid thermosynthesis method adopted in the invention has the advantages of simplicity andconvenience in operation (normal pressure), high specific surface area of the prepared material and the like. Hypophosphite (H2PO<2->, phosphorus of +1 valence state) with high reducing property serves as a reducing agent and a phosphorus source, so that the reaction temperature can be greatly reduced, and the energy consumption is reduced.

Description

technical field [0001] The invention specifically relates to a preparation method of a vanadyl phosphate catalyst and its application in catalytic oxidation reactions. Background technique [0002] The research on the synthesis of vanadyl phosphate catalyst mainly focuses on the preparation of the precursor. The precursor hydrogen phosphate hemihydrate is usually generated by vanadium pentoxide and phosphoric acid under the reducing agent. 5+ effectively reverts to V 4+ , and then form a vanadyl phosphate precursor with a clear crystal phase (such as VOHPO 4 1 / 2H 2 O). Broadly include the following routes: [0003] (1) VPA route. This method uses water as solvent and hydrochloric acid as reducing agent to prepare VOHPO 4 1 / 2H 2 O. Later, people began to change the reducing agent, such as lactic acid and oxalic acid. The precursor hydrogen phosphate hemihydrate synthesized by this route is a large irregular shape with a very low specific surface area (3m 2 / g), and ...

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Problems solved by technology

Although the direct dehydrogenation process is simple to operate, due to the Cu-Zn / Al 2 o 3 The catalyst also has hydrogenation activity, so the reaction is a reversible reaction, controlled by thermodynamic equilibrium, and there is an equilibrium conversion rate, which limits the room for improvement of the conversion rate