Maximizing Biojet Fuel Production from Triglyceride: Importance of the Hydrocracking Catalyst and Separate Deoxygenation/Hydrocracking Steps

Abstract

Various parameters in the catalytic hydroconversion of triglycerides (palm oil) were carefully investigated for maximizing the production of biojet fuel. The results showed that the deoxygenation of triglyceride via hydrotreatment should be carried out in a separate reactor prior to the hydrocracking step (i.e., two-step reaction process). Otherwise, the CO generated during deoxygenation can poison the metal components in the metal/acid bifunctional catalysts (Pt/zeolites), which can cause significant imbalance between the metal and acid functions in hydrocracking. This leads to fast catalyst deactivation via coke formation, heavy formation of aromatics, and overcracking of hydrocarbons, resulting in the reduction of final biojet fuel yield. In the two-step process, the second hydrocracking step mainly determines the final biojet fuel yield, and thus, a rational design of the hydrocracking catalysts that can suppress overcracking is essential. The diffusion characteristics of the multibranched hydrocarbon (e.g., 2,2,4-trimethylpentane) in the hydrocracking catalysts could be correlated with the yields of the jet fuel-range C8–C16 hydrocarbons and the iso/n-paraffin ratios. The result indicates that the facile diffusion of multibranched isomers out of catalysts before excessive cracking is important for the suppression of the formation of light hydrocarbons (≤C7). Consequently, Pt supported on nanocrystalline large-pore BEA zeolite showed the largest biojet fuel yield with the highest iso-paraffin content. Under the optimized conditions, 55 wt % of biojet fuel with respect to palm oil was achieved after final distillation, which satisfied all the required fuel specifications.

Confinement Effects in Zeolite‐Confined Noble Metals

“…dehydrogenation, dehydrocyclization, hydroisomerization, hydrocracking) Pt/ZSM-5 [89] ,Pt/ZSM-22 [90] ,Pt/HZSM-5 [91] ,Pt/USY [92] ,P t/ZSM-5, % /Beta. [93] Angewandte Chemie with larger microscale bulk metals because of more exposed active sites per molar amount of metal. [40] In the last decade, the rapid development of the above-mentioned synthesis strategies provides ag ood chance to understand the unique mechanism and effects of different sizes of nanometals in zeolites.P article sizes of nanometals in zeolites have been precisely controlled, for example,n anoscale sizes by nanoencapsulation, subnanoscale sizes by traditional impregnation and atomic-scaled sites by framework fixation.…”

An Intensified Reactive Separation Process for Bio-Jet Diesel Production

“…Specifically, for the production of jet diesel, the catalysts are bifunctional and are characterized by having acid sites that allow the selective function of isomerization and cracking simultaneously. Experimental evidence [34] indicate that the conversion of the n-paraffins can be described by the following reactions network:…”

“…The exit stream from the isomerization-cracking reactor is further flashed to eliminate the hydrogen excess and the light hydrocarbons produced during the cracking step. The isomerization-cracking kinetics and reactor arrangement were taken from the open literature [34]. From Table 3 it can be observed that the bio-jet-diesel produced contains mainly i-C 8 to i-C 16 hydrocarbons indicating that a light bio-jet diesel is produced.…”

Bioavtur Synthesis from Palm Fatty Acid Distillate through Hydrotreating and Hydrocracking Processes

“…Over-cracking would cause in the production of hydrocarbons in biogasoline range, as was reported by Kim et al when using a highly acidic catalyst, platinum on zeolite catalyst. (Kim, Kim, Lee, Lee, & Choi, 2017) After the hydrotreating and hydrocracking processes, the samples were expected to have a lower free fatty acid content compared to the PFAD after the reaction through hydrotreating mechanisms. The result of FFA left in the sample, and FFA conversion from the experiments is shown in Figure 1.…”