Characteristics and Kinetics of Coked Catalyst Regeneration via Steam Gasification in a Micro Fluidized Bed

Abstract

Petroleum residue cracking combined coke gasification (RCCG) process was proposed to regenerate the catalyst via coke-steam gasification for syngas production, thus to solve the problem of excessive heat generated via coke combustion in the industrial fluid catalytic cracking (FCC) process. A commercial FCC catalyst and a bifunctional (BF) catalyst were used as the candidates for the RCCG process, and the BF catalyst was specially designed with both catalytic effects of oil cracking and coke gasification. The regeneration characteristics and kinetics of FCC and BF catalysts were studied using a micro fluidized bed. The results showed that high-quality syngas was produced when regenerating the catalysts via steam gasification and the sum of H2 and CO in the produced gas was over 80 vol % under electrically heated condition.The gasification rate first increased with increasing carbon conversion and then slowly decreased. In comparison with FCC catalyst, the regeneration time of BF catalyst was shortened by more than 30% via addition of alkaline metal oxides and adjustment of its pore size. Homogenous model (HM) and shrinking core model (SCM) were used to calculate the regeneration kinetic parameters of coked catalysts. It was found that the activation energies from these two models were close to each other, while HM had a better fitting relevance for the data than SCM. The activation energy of BF catalyst regeneration was about 115 kJ·mol–1, lower than that of FCC catalyst (150 kJ·mol–1), demonstrating that BF catalyst was easier to regenerate via coke gasification and also justified its bifunctional characteristics. The activation energy of coke gasification on BF catalyst could be further decreased to 45 kJ·mol–1 when introducing 3% oxygen as the gasification reagent.

Regeneration of catalysts deactivated by coke deposition: A review

“…The gasification kinetics of these two catalysts were also evaluated. The activation energy of BFC was about 115 kJ/mol lower than that of the commercial FCC catalyst (150 kJ/mol), indicating that alkaline metal oxide doping can accelerate the gasification rate [119]. They also studied the effects of catalyst structure and operating parameters on steam coke gasification [120].…”

“…They selected O2 (2 kPa) and steam (90 kPa) as the gas mixture to study kinetics and observed the activation energy decreasing from 230 kJ/mol (pure steam) to 90 kJ/mol and decided to better use the shrinking-core model rather than the homogeneous model to describe the gasification behavior. Using the BFC catalyst, Zhang et al [119] introduced 3% O2 to the steam and found a significant decrease in regeneration time. They showed, coke Fig.…”

Upgrading of Canadian Oil Sand Bitumen via Cracking and Coke Gasification: Effect of Catalyst and Operating Parameters

“…Actually, we have studied regeneration of coked catalysts using a micro fluidized bed reactor by pulse feeding the cokecoated catalysts at 800 °C, finding that the regeneration time of the BFC catalyst was greatly shortened within 30 min by this isothermal operation. 27 Nevertheless, clear differences in coke gasification rate could be seen between FCC and BFC catalysts. Also, the nascent hot coke during the in situ catalyst regeneration would have higher reactivity than the nonporous cold petroleum coke from delayed coking.…”

A Review on Biomass Gasification: Effect of Main Parameters on Char Generation and Reaction

“…Alternatively, the ash layer over the particles could be entrained away via particle attrition or gas flow under some severe operating conditions, making it different from the model assumption of the previous condition. While these SCM, HM, and RVP models are widely used to describe solid particle consumption, such as the burning of coal particles and regeneration of coked catalysts, nowadays char gasification has also been studied kinetically using different reaction models. , …”