HDS AND HDN ACTIVITY AND CHARACTERIZATION OF NiMo ‐USY ZEOLITE CATALYSTS

Abstract

INTRODUCTIONHydrotreating reactions such as HDS, HDN and HC are usually conducted on mixed transition metal sulfides (Ni-Mo or NI-W) supported on carriers which are more or less acidic depending on the function to be promoted (1). As pointed out by Pratt et al.(2) the carrier has a marked effect on the specific activity of the sulfide catalysts. However, alumina, which is the most used carrier for this type of catalysts, offers only a moderate cracking activity and requires severe hydrotreating of the feedstock and compiete nitrogen removal. For these reasons, mixed sulfides dispersed on more acidic materials as silica-alumina or zeolites appear quite attractive. The incorporation of small amounts of zeolites into typical commercial hydrotreating catalysts led to significant activity improvement (3) because with thls type of modification were obtain more acidic catalysts than those supported on aiuminas or silica-aluminas. Such catalysts yield more desired products (light hydrocarbons and gasoiins) and are more resistant to poisoning by Sand N-containing compounds present in the feed (4,5).Many studies have been devoted to investigate the distribution of nickel and molybdenum in calcined HY zeolites (6-12), although only few dealt with their sulfided counterparts (13-16). However, these latter studies can be conclusive in the point that suifidation at high pressure conditions causes important structural modifications of the precursor phases, and even of the zeolite substrate. As it is well known, the USY zeolite has a very low ion exchange capacity which limits the feasibility to obtain metal-loaded zeolite catalysts with highly dispersed active ingredients across the crystal. As a consequence, the incorporation of both Ni and Mo components into USY zeolites usually leads to deposit the active ingredients at the external surface. As the dimensions of the channels of Y zeolites are too small as to facilitate the incorporation of voluminous anions of salts of Mo, non-conventional preparation methods have to be used to overcome these difficulties. Accordingly, this work was undertaken with the aim to compare catalytic

Role of the Ru and Support in Sulfided RuNiMo Catalysts in Simultaneous Hydrodearomatization (HDA), Hydrodesulfurization (HDS), and Hydrodenitrogenation (HDN) Reactions

“…The Mo 3d 5/2 peak of all spent catalysts exhibited binding energy at 229.3 eV because of MoS 2 species . In this study, all catalysts showed complete sulfidation of molybdenum species.…”

Preparation and Evaluation of the Composite Containing USL Zeolite-Supported NiW Catalysts for Hydrotreating of FCC Diesel

“…However, high acidity of zeolites will result in deep cracking or secondary reactions in the catalytic processes. For the deep desulfurization reactions, for example, it should be required a suitable degree of acidic functionality in order to improve the ring-opening of heterocyclic aromatic components, which is prior to the conversions of organic heteroatomic compounds to inorganic sulfur and nitrogen species . It has been reported that the incorporation of acidic zeolites in catalysts could promote the hydroisomerization and dealkylation activities of a catalyst. , On the other hand, these acidic materials tended to possess either only micropores (less than 2 nm) or only mesopores (2−50 nm), in most cases only micropores .…”