The dependence of ZSM-5 additive performance on the hydrogen-transfer activity of the REUSY base catalyst in fluid catalytic cracking

摘要: Abstract The trend in the FCC industry is towards increasing rare-earth content of REUSY catalysts. Such catalysts provide higher acid site density than at lower concentrations, which enhances both cracking rate and hydrogen-transfer activities. beneficial effects activity are reduction gasoline olefinicity yields. Increasing unit-cell size also has undesired effect reducing C3–C5 olefins. In practical applications this trade-off smaller olefins often corrected by use ZSM-5 containing additives. order to quantify varying base catalyst on performance, with different contents were blended a additive. These combinations investigated microactivity test unit short contact-time, high temperature heavy vacuum gas-oil. Earlier studies have shown that effectiveness was decreased catalyst. had two effects: enhanced lowered olefinicity. A detailed analysis data revealed these tend reduce effectiveness. work, investigation reactivity accomplished experiments feeds crackability yielding olefin yields fraction. following shifts observed product distribution: ratios propene-to-i-butene increased significantly degree depletion range study shows addition isomerisation; i-butene i-pentene formation shifted thermodynamic equilibrium. more pronounced low activity. experimental settings used work been produce being relatively close those riser pilot plants therefore, provides some guidance regard commercial application