Use of composite catalyst using 4A molecular sieve a main ingredient for producing ethylene from low-temperature dehydration of ethyl hydrate

The invention discloses a compound catalyst for preparing ethylene by catalyzing ethanol to dewater under a lower temperature. The catalyst is a compound catalyst which takes a 4A molecular sieve as a main component and takes TiO2 as an addition agent. The invention also discloses a preparation method for the compound catalyst which comprises the following steps: taking a proper amount of the 4A molecular sieve which is cleaned and dried and completely dipped into the mixed solution of ammonium fluorotitanate solution and boric acid solution to deposit with a depositing time of 1 to72h; the mixed solution is acted to obtain the compound catalyst of the 4A molecular sieve/TiO2 on which a TiO2 deposition layer is formed; the compound catalyst is dried in an oven and then is thermally treated in a muffle, is naturally cooled to obtain the compound catalyst of the 4A molecular sieve/TiO2 the surface of which is an anatase TiO2 deposition layer. The adpotion of the compound catalyst prepared by the method can redu