Catalytic cracking of model compounds of bio-oil over HZSM-5 and the catalyst deactivation

Highlights: • The catalytic cracking of model compounds with various functional groups was investigated. • The tendency of carbon yield decreases: n-heptane > cyclohexane > acetic acid > ethyl acetate > guaiacol > acetol. • Catalysts deactivation follows the trend of furfural > acetol > guaiacol > acetic acid > ethyl acetate > cyclohexane > n-heptane. • Acetic acid produces the highest yield of olefins (68.3%). The catalytic cracking upgrading reactions over HZSM-5 of different model compounds of bio-oil have been studied with a self-designed fluid catalytic cracking (FCC) equipment. Typical bio-oil model compounds, such as acetic acid, guaiacol, n-heptane, acetol and ethyl acetate, were chosen to study the products distribution, reaction pathway and deactivation of catalysts. The results showed: C₆–C₈ aromatic hydrocarbons, C₂–C₄ olefins, C₁–C₅ alkanes, CO and CO₂ were the main products, and the selectivity of olefins was: ethylene > propylene > butylene. Catalyst characterization methods, such as FI-IR, TG-TPO and Raman, were used to study the deactivation mechanism of catalysts. According to the catalyst characterization results, a catalyst deactivation mechanism was proposed as follows: Firstly, the precursor which consisted of a large number of long chain saturated aliphatic hydrocarbons and a small amount CC of aromatics formed on the catalyst surface. Then the active sites of catalysts had been covered, the coke type changed from thermal coke to catalytic coke and gradually blocked the channels of the molecular sieve, which accelerated the deactivation of catalyst.