ZrO_2-Al_2O_3 composite carriers modified by P element were prepared by sol-gel method and additive modification method, and the influence of different ZrO_2 contents and P modification on physical properties and acidity of composite carriers were examined; The results showed when ZrO_2 contents were 3~5%, there was little difference for specific surface area and pore structures, but carrier acidity was increased and the catalyst activity was improved. P additive could adjust carrier activity and weaken the...