Influence of oxalate ligand functionalization on Co/ZSM-5 activity in Fischer Tropsch synthesis and hydrodeoxygenation of oleic acid into hydrocarbon fuels

Abstract

Achieving high degree of active metal dispersions at the highest possible metal loading and high reducibility of the metal remains a challenge in Fischer Tropsch synthesis (FTS) as well as in hydrogeoxygenation (HDO).This study therefore reports the influence of oxalic acid (OxA) functionalization on the metal dispersion, reducibility and activity of Co supported ZSM-5 catalyst in FTS and HDO of oleic acid into paraffin biofuel. The Brunauer–Emmett–Teller (BET) results showed that cobalt oxalate supported ZSM-5 catalyst (CoOx/ZSM-5) synthesized from the incorporation of freshly prepared cobalt oxalate complex into ZSM-5 displayed increase in surface area, pore volume and average pore size while the nonfunctionalized cobalt supported on ZSM-5 (Co/ZSM-5) catalyst showed reduction in those properties. Furthermore, both XRD and XPS confirmed the presence of Co° formed from the decomposition of CoOx during calcination of CoOx/ZSM-5 under inert atmosphere. The HRTEM showed that Co species average particle sizes were smaller in CoOx/ZSM-5 than in Co/ZSM-5, and in addition, CoOx/ZSM-5 shows a clear higher degree of active metal dispersion. The FTS result showed that at CO conversion over Co/ZSM-5 and CoOx/ZSM-5 catalysts were 74.28% and 94.23% and their selectivity to C5+ HC production were 63.15% and 75.4%, respectively at 4 h TOS. The HDO result also showed that the CoOx/ZSM-5 has higher OA conversion of 92% compared to 59% over Co/ZSM-5. In addition CoOx/ZSM-5 showed higher HDO and isomerization activities compared to Co/ZSM-5.

Recent Advances in Bifunctional Catalysts for the Fischer–Tropsch Process: One-Stage Production of Liquid Hydrocarbons from Syngas

“…61 This was explained by the increased reducibility in the active metal site. Some authors have worked to elucidate the effect of particle localization, whether in the external surface of the support 61,131 or inside the pores, 83,116,132 on catalytic performance. Yao et al 61 and Lu et al 130 have demonstrated that the catalyst synthesis method has a significant effect on metal particle localization, with the PEG additive method resulting in the deposition of most Co 3 O 4 particles on the outer surface of ZSM-5, which increases the metal reducibility (up to 31%).…”

Engineering the Catalytic Properties of HZSM5 by Cobalt Modification and Post-synthetic Hierarchical Porosity Development

“…H 2 -TPR ( Fig. 2) revealed the main reduction peaks at temperatures lower than 400 °C which are ascribed to the reduction of Co 3 O 4 that proceeds via a multistep mechanism (reduction of Co 3 O 4 to CoO and then to metallic Co) [29,30].…”

Hydrodeoxygenation of oleic acid for effective diesel-like hydrocarbon production using zeolite-based catalysts

“…Noted, the OA conversion also even higher than former finding (83%) [46], implying the high OA conversion rate was attributed to the elevated reaction temperature (300-400 °C). Overall, HZSM5 demonstrated lesser OA conversion, possibly due to its lower acidity and existence of strong acid sites which tends to adsorb strongly the oxygenated species, resulting in total coverage of HZSM5 active species [47]. A high coverage of oxygenates species reduces HZSM5 HDO activity and consequently OA conversion.…”