To reduce the carbon footprint and greenhouse gas (GHG)
emissions
associated with heavy crude oil/bitumen upgrading and refining in
the production of clean transportation fuels, researchers are targeting
the production of fuels from renewable energy resources. These resources
are mainly biomass-derived oils, which include oils produced by biomass
pyrolysis (bio-oil), edible and inedible vegetable oils, and animal
fats. Over the past 2 decades, research has focused on the evaluation
of biomass-derived oil processing using conventional fluid catalytic
cracking (FCC), a technology responsible for producing the majority
of gasoline in a petroleum refinery. The present review summarizes
research associated with the FCC of various biomass-derived oil feedstocks
as well as studies related to the co-processing of these oils with
conventional petroleum feedstocks. The objective of this review is
to present a comprehensive perspective of the effects of renewable
oil processing on existing FCC technology, operation, catalysts, and
product quality and quantity.
Concerns over the declining availability of light conventional crude oils coupled with increasing energy demands and growing environmental concerns have sparked a global interest in the use of renewable oils as potential feedstocks for biofuel production. Over the past 2 decades, a considerable number of research studies in the area of renewable oil processing has been conducted around the world. The present review summarizes recent progress in processing biomass-derived oils, such as pyrolysis bio-oils, edible/inedible vegetable oils, and animal fats, and co-processing these oils with petroleum feedstocks using conventional hydroprocessing technologies, such as hydrotreating and hydrocracking. The main focus of this review is to provide an understanding of the effects of biomass feedstocks on process operation, catalyst performance and deactivation, feedstock conversion, and product yield and quality.
Catalytic conversion of cycloparaffins is a complex process involving competing reaction steps. To understand this process, FCC experiments using methylcyclohexane (MCH) on USY zeolite catalysts were carried out in the mini-fluidized CREC riser simulator. Runs were developed under relevant FCC process conditions in terms of partial pressures of MCH, temperatures (450-550 C), contact times (3-7 s), catalyst-oil mass ratios (5), and using fluidized catalysts. MCH overall conversions ranged between 4 to 16 wt %, with slightly higher conversions obtained using the larger zeolite crystallites. Moreover, it was found that MCH undergoes ring opening, protolytic cracking, isomerization, hydrogen transfer and transalkylation. A heterogeneous kinetic model for MCH conversion including thermal effects, adsorption and intrinsic catalytic reaction phenomena was established. Adsorption and kinetic parameters were determined, including the heat of adsorption (À40 kJ/mol), as well as thermal and primary catalytic intrinsic activation energies, which were in the range of 43-69 kJ/mol, and 50-74 kJ/mol, respectively. V
Catalytic cracking experiments of vacuum gas oil on fluid catalytic cracking (FCC)-type catalysts are carried out in a fluidized bench-scale batch Chemical Reactor Engineering Centre (CREC) riser simulator reactor. These experiments are conducted under operating conditions similar to those of the industrial FCC process in terms of temperature, catalyst-to-oil ratio, partial pressure of reactant and products, and reaction times. The crystallite size of the supported zeolite is varied between 0.4 and 0.9 microns with both activity and selectivity being monitored. A five-lump kinetic model describing the catalytic cracking of vacuum gas oil is considered, which accounts for diffusional constraints experienced by hydrocarbon species while evolving in the zeolite pore network. This study provides insights into the effect of intracrystalline diffusion in the catalytic cracking of heavy feedstocks. Results show that the catalyst with the smaller crystallite size provides higher activity and selectivity for desirable intermediate products (gasoline) and lower selectivity for terminal products (coke).
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