The invention relates to a modified ZSM-5
molecular sieve catalyst used for
toluene methanol alkylation, which takes a ZSM-5
molecular sieve as a matrix,
molecular sieve raw
powder is taken as a commodity
reagent, its scaled silica-
alumina ratio (nSiO2 / nAl2O3) is 25, the particle sizes can be divided into two types, the primary particle size of the
large particle size (or conventional particle size) ZSM-5 belongs to the micron order, the primary particle size of the
small particle size ZSM-5 is about 200 nanometers, tetraethoxysilane (TEOS) is taken as a
silicon source, an external surface and hole opening of the molecular
sieve can be modified through chemical
liquid phase deposition, the SiO2 deposition amount is between 3% and 25%, or
chemical modification of Ni and P elements is employed, and the contents of Ni and P elements are 0-1% and 0-8%. According to the invention, the modified ZSM-5 molecular
sieve catalyst can be used for preparing
xylene by the
toluene methanol alkylation with high catalytic activity, the conversion for per pass of
toluene can reach more than 30%, in three types of
xylene products, the selectivity on
xylene is higher than 90%, and the modified ZSM-5 molecular
sieve catalyst of the invention is the catalyst possessing
high activity and
high selectivity.