An overview of new approaches to deep desulfurization for ultra-clean gasoline, diesel fuel and jet fuel

Recent advances in the science and technology of ultra low sulfur diesel (ULSD) production

This paper is a selective review on design approaches and associated catalysis and chemistry for deep desulfurization and deep dearomatization (hydrogenation) of hydrocarbon fuels, particularly diesel fuels. The challenge for deep desulfurization of diesel fuels is the difficulty of removing the refractory sulfur compounds, particularly 4,6-dimethyldibenzothiophene, with conventional hydrodesulfurization processes. The problem is exacerbated by the inhibiting effect of polyaromatics and nitrogen compounds, which exist in some diesel blend stocks on deep HDS. With the new Environmental Protection Agency (EPA) Tier II regulations to cut the diesel sulfur from current 500 ppmw down to 15 ppmw by June 2006, refineries are facing major challenges to meet the fuel sulfur specification along with the required reduction of aromatics contents. The principles and problems for the existing hydrodesulfurization processes, and the concepts, advantages and disadvantages of various new approaches will be discussed. Specifically, the following new design approaches for sulfur removal will be discussed: (1) novel catalysts for ultra-deep hydrodesulfurization under conventional HDS process conditions; (2) new design concept for sulfur-tolerant noble metal catalysts for low-temperature hydrogenation; (3) new desulfurization process by sulfur adsorption and capture under H2; (4) new desulfurization process by selective adsorption at ambient temperature without H2 and a related integrated process concept; (5) oxidative desulfurization in liquid-phase; and (6) biodesulfurization.

New design approaches to ultra-clean diesel fuels by deep desulfurization and deep dearomatization

Sulfur compounds represent one of the most common impurities present in the crude oil. Sulfur in liquid fuel oil leads directly to the emission of SO2 and sulfate particulate matter (SPM) that endangers public health and community property; and reduces the life of the engine due to corrosion. Furthermore, the sulfur compounds in the exhaust gases of diesel engines can significantly impair the emission control technology designed to meet NOx and SPM emission standards. The research efforts for developing conventional hydrodesulfurization and alternative desulfurization methods such as selective adsorption, biodesulfurization, oxidation/extraction (oxidative desulfurization), etc. for removing these refractory sulfur compounds from petroleum products are on the rise. Research laboratories and refineries are spending huge amounts of money in finding a viable and feasible solution to reduce sulfur to a concentration of less than 10 mg l−1. This paper reviews the current status in detail of various desulphurization techniques being studied worldwide. It presents an overview of novel emerging technologies for ultra-deep desulfurization so as to produce ultra-low-sulfur fuels.

An evaluation of desulfurization technologies for sulfur removal from liquid fuels

In situ Mössbauer emission spectroscopy studies of unsupported and supported sulfided CoMo hydrodesulfurization catalysts: Evidence for and nature of a CoMoS phase

https://pure.tue.nl/ws/files/2498592/620480.pdf

Hydrodesulfurization of methyl-substituted dibenzothiophenes catalyzed by Co-Mo/gamma-Al2O3

Kinetics experiments have determined the reaction network in the hydrodesulfurization of dibenzothiophene catalyzed by sulfided CoO-MoO3/γ-Al2O3 at 573°K and 102 atm The predominant reaction is a direct sulfur extrusion, giving biphenyl and hydrogen sulfide; the biphenyl is subsequently hydrogenated slowly to give cyclohexylbenzene and then bicyclohexyl Dibenzothiophene also undergoes a primary hydrogenation reaction preceding sulfur removal, but it is about one thousand times slower than the sulfur extrusion reaction

D.H. Broderick

Papers

Hydrodesulfurization of methyl-substituted dibenzothiophenes catalyzed by Co-Mo/gamma-Al2O3

Hydrodesulfurization of dibenzothiophene catalyzed by sulfided CoO-MoO3γ-Al2O3: The reaction network

Hydrogenolysis and hydrogenation of dibenzothiophene catalyzed by sulfided CoO-MoO3/γ-Al2O3: The reaction kinetics

Hydrodesulfurization of polycyclic aromatics catalyzed by sulfided CoOMoO3γ-Al2O3: The relative reactivities

The sulfided CoMoγ-Al2O3 catalyst: Evidence of structural changes during hydrodesulfurization of dibenzothiophene