Solid acid catalyst and preparation method thereof, and preparation method of diolefin compounds

The invention provides a solid acid catalyst which comprises a silicoaluminophosphate molecular sieve and an assistant, wherein the silicon-aluminum-phosphorus mol ratio in the silicoaluminophosphate molecular sieve is (0.005-2.5):1:(0.1-5). The solid acid catalyst provided by the invention can catalyze condensation reaction between carboxylic compounds disclosed as Formula (I) and mono-olefin compounds disclosed as Formula (II) to prepare the diolefin compounds. The solid acid catalyst provided by the invention has higher product selectivity, reduces the possibility of side reactions in the condensation reaction process, and enhances the yield of the diolefin compounds. Besides, the solid acid catalyst provided by the invention has high catalytic activity and higher conversion rate. In addition, the solid acid catalyst provided by the invention has the advantages of low toxicity, long service life and favorable regenerability, and is suitable for industrial production.