Perspectives on strategies for improving ultra-deep desulfurization of liquid fuels through hydrotreatment: Catalyst improvement and feedstock pre-treatment

Abstract

Reliance on crude oil remains high while the transition to green and renewable sources of fuel is still slow. Developing and strengthening strategies for reducing sulfur emissions from crude oil is therefore imperative and makes it possible to sustainably meet stringent regulatory sulfur level legislations in end-user liquid fuels (mostly less than 10 ppm). The burden of achieving these ultra-low sulfur levels has been passed to fuel refiners who are battling to achieve ultra-deep desulfurization through conventional hydroprocessing technologies. Removal of refractory sulfur-containing compounds has been cited as the main challenge due to several limitations with the current hydroprocessing catalysts. The inhibitory effects of nitrogen-containing compounds (especially the basic ones) is one of the major concerns. Several advances have been made to develop better strategies for achieving ultra-deep desulfurization and these include: improving hydroprocessing infrastructure, improving hydroprocessing catalysts, having additional steps for removing refractory sulfur-containing compounds and improving the quality of feedstocks. Herein, we provide perspectives that emphasize the importance of further developing hydroprocessing catalysts and pre-treating feedstocks to remove nitrogen-containing compounds prior to hydroprocessing as promising strategies for sustainably achieving ultra-deep hydroprocessing.

Unblocking of NiMo Active Sites for Hydrodesulfurization Catalysts: A Study Focused on Inactive NixSy Segregation

“…Therefore, these bulky sulfur compounds generally prefer the HYD route as steric hindrance reduced during the hydrogenation step. In this work, the prepared catalysts represent DDS as the dominant reaction route but with enhanced HYD selectivity as compared to conventional catalysts, which increased the probability of attaining complete sulfur removal …”

“…In this work, the prepared catalysts represent DDS as the dominant reaction route but with enhanced HYD selectivity as compared to conventional catalysts, which increased the probability of attaining complete sulfur removal. 47 Figure 8 shows the product distribution graph for the HDS reaction of DBT for the prepared catalysts after the leaching process (data also presented in Table S4, Supporting Information). At each temperature, the formation of the biphenyl (BP) product was more than CHB for all prepared catalysts suggesting that BP is the main product of the reaction, but it was maximum for conventional wet-impregnated catalysts.…”

Pursuing the End-of-Life Tire Circularity: An Outlook toward the Production of Secondary Raw Materials from Tire Pyrolysis Oil

“…Upon completion, H 2 S (in the case of sulfur) or NH 3 (in the case of nitrogen) are produced, leaving behind the corresponding hydrocarbons. 161 On the other hand, HDC aims at transforming heavy oil fractions into more valuable middle distillates (e.g., reduce the boiling point range of the feed) by applying more severe conditions than those of HTO. 120 Figure 18 161 displays some of the hydroprocessing pathways and their related operating conditions in conventional refineries.…”

“…161 On the other hand, HDC aims at transforming heavy oil fractions into more valuable middle distillates (e.g., reduce the boiling point range of the feed) by applying more severe conditions than those of HTO. 120 Figure 18 161 displays some of the hydroprocessing pathways and their related operating conditions in conventional refineries. The most common catalysts used in HTO processes are alumina-supported in cobalt−molybdenum (CoMo) and nickel−molybdenum (NiMo).…”

Synthesis, crystal structures and DFT studies of Co(ii) and Zn(ii) coordination polymers of terephthalate and 4,4′-trimethylenedipyridyl ligands for removal of dibenzothiophene from a model fuel oil

“…In addition to the large amounts of hydrogen and the high temperature and pressure required, failure of achieving ultra-low sulfur levels through HDS has motivated the continual improvement of alternative or complementary methods such as biodesulfurization, oxidative desulfurization, extractive desulfurization, and adsorptive desulfurization. [3][4][5][6] Among these methods, adsorptive desulfurization has been gaining attention over the years especially with the advent of several potential adsorbent materials that offer attractive properties. 4 Adsorption occurs through a range of mechanisms such as size exclusion, and chemical and physical interactions.…”