Hydrotreating catalyst development

Resid hydrotreating catalysts, developed in 1987 have been used together with a scale-and iron-removing catalyst for (1) the cracking and desulfurization of atmospheric residue, (2) the pretreatment of RFCC and (3) the cracking of vacuum residue. Approximately 7000 tons of industrial catalysts have been used in commercial units so far. 

OptiCAT-plus A process for regenerating hydrotreating catalysts. It uses a fluidized-bed pretreatment to control the initial exotherms found in regeneration, followed by a moderate heat soak to eliminate sulfur and carbon. Developed in the 1990s by the Criterion Catalyst Company. 

The Exxon Donor Solvent (EDS) Process, developed by the Exxon Research and Engineering Co., differed from the typical process in that, before being recycled, the solvent was hydrogenated in a fixed-bed reactor using a hydrotreating catalyst, such as cobalt or nickel molybdate. Exxon found that use of this hydrogen donor solvent with carefully controlled properties improved process performance. Exxon developed a solvent index, based on solvent properties, which correlated with solvent effectiveness. 

Hydrotreating catalysts originated in the 1920s when German researchers developed unsupported metal sulfide catalysts to liquefy coal. However, it was not until the 1970s that the structures of these catalysts and the mechanisms of their catalytic action began to be understood. It was established that under catalytic reaction conditions, most of the molybdenum in industrial... 

As observed from simulations, the formulated HDM catalyst deactivation model based on the percolation approach can predict metal deposition profiles and catalyst life time. In the industrial application of hydrotreating catalysts metal deposition maxima are observed in spent catalysts, which is in qualitative agreement with the developed model... 

The feasibility of hydrotreating whole shale oil is demonstrated by means of several long pilot plant tests using proprietary commercial catalysts developed by Chevron. One such test was on stream for over 3500 hr. The rate of catalyst deactivation was very low at processing conditions of 0.6 LHSV and 2000 psia hydrogen pressure. The run was shut down when the feed supply was exhausted although the catalyst was still active. 

Hydrotreating catalysts are usually alumina supported molybdenum based catalysts with cobalt or nickel promotors. By 1990, the demand for hydrotreating catalysts is expected to reach 80,000,000 pounds annually (1). The increased demand for these catalysts and the limitations on the availability and supply of the active metals increase the urgency to develop effective catalyst regeneration techniques. 

SCANfining A selective catalytic hydrotreating process for reducing the sulfur content of naphtha. Developed by ExxonMobil and Albemarle. The catalyst, developed by ExxonMobil and Akzo Nobel, contains cobalt and molybdenum. The key feature is its prevention of the mercaptans reversion reaction — the formation of mercaptans from olefins and hydrogen sulfide. The process also minimizes olefin saturation and hydrogen loss. To be used at the Bazan Oil Refinery, Israel, from 2001, and at the Statoil refinery at Mongstad, Norway. Also planned for use in the Williams refinery in Memphis, TN. 

Researchers at Haldor Topsoe and their collaborators in academic institutions have contributed significantly to both the advances in research on fundamental aspects of catalytically active sites of transition metal sulfides and the development of new and more active commercial hydrotreating catalysts and processes.15 79 80... 

It is well-known that a new generation of hydrotreating catalysts prepared with a silica promoted alumina support has been developed and are in use in a number of commercial hydrotreating units. Improved and more flexible operation should be possible especially in thermally cracked feedstocks with these catalysts having a higher HDS activity and resistance to carbon deposition than conventional CoMo or NiMo catalysts. 

Model 1-6 is a new hydrodearomatization (HDA) catalyst developed by ICERP to be used in aromatics hydrogenation of gas oil blends. The catalyst has been obtained by a highly improved NiO dispersion on the promoted alumina support having a bimodale pore distribution with a total pore volume of minimum 45 cmVg. 1-6 has a good HDA activity under rather moderate hydrotreating conditions i.e. 60 bar total pressure and a remarkable sulphur resistance. 

As illustrated earlier, for various forms of more conventional hydrocracking, the type of catalyst used can influence the product slate obtained. For example, for a mild hydrocracking operation at constant temperature, the selectivity of the catalyst varies from about 65% to about 90% by volume. Indeed, several catalytic systems have now been developed with a group of catalysts, specifically, for mild hydrocracking operations. Depending on the type of catalyst, they may be run as a single catalyst or in conjunction with a hydrotreating catalyst. 

A bimetallic hydrotreating catalyst, tailored for this kind of feedstock, has been developed and tested under different conditions and the main results are summarized here. 

The necessity to develop hydrotreating catalysts with enhanced activity stimulates the search for alternative catalyst supports. It was shown that clay-supported transition metal sulfides can efficiently catalyze hydrodesulfurization (HDS) of thiophene [1-3]. However, the large scale application of the catalysts based on natural clays is still hampered, mainly due to the difficulties in controlling the chemical composition and textural properties. Synthetic clays do not suffer from these drawbacks. Recently, a novel non-hydrothermal approach was proposed for the synthesis of some trioctahedral smectites, namely saponite... 

A breakthrough distillate hydrotreating catalyst, jointly developed by ExxonMobil and AkzoNobel, was recently commercialized and deployed in three refineries. This catalyst has three to ten times the activity of the most active current HDS/HDN catalysts, depending on pressure. This catalyst also exhibits novel and unique pressure sensitivity from 400 psi Hydrogen-2 pressure up to 2,000 psi Hydrogen-2. It represents a major advance in catalyst performance, composition, structure, and morphology. The product is stripped not only of sulfur but also nitrogen and achieves substantial aromatic saturation. 

The mechanisms and role of coke deposition on hydrotreating catalysts during the very first hours of a run were investigated under different conditions. A HPLC method has been developed for separation of oils into fractions containing aliphatics, monoaromatics, diaromatics, triaromatics and PNAs including the N-containing compounds- With this method it is possible to identify the fractions that may be responsible for coke formation. Tests with various feeds (with different distribution at aromatic fractions) showed that the only fraction that correlates with the amount of coke is the PNA fraction. 

S. P. Ahuja, M. L. Derrien, and J. F. Lepage, Activity and Selectivity of Hydrotreating Catalysts, Industrial and Engineering Chemistry Product Research and Development 9(3) 272-281 (1970). 

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