NiMo catalysts

HYDROPROCESSING OF 33% BLEND OF SHORT-CONTACT TIME SRC (Pressure 13790 kPa NiMo Catalyst)... 

Certain catalyst manufacturers claims to have optimized the preparation (CoMo catalysts), the formulation or the promotion (aromatic saturation) of their catalysts to achieve an appropriate balance of the hydrogenation function to desulfurize the sterically hindered compounds and yield the 15 ppm S fuel. However, the actual trend is to use NiMo catalyst for the treatment of the more refractory compounds, below 200 ppm S [22],... 

Resids HDT is carried out at temperatures between 360°C and 450°C, pressures from about 1500 to 3000psig, and 0.2 to lh-1 of space velocity. Graded catalyst beds combining CoMo and NiMo catalysts can be adapted to the quality of the feedstock and depending on whether atmospheric or vacuum residues are going to be treated. HDT of resids is seen as a feedstock pretreatment for preparing feedstock for either mixed with ordinary FCC feeds or for HCK (mixed with VGO or to a resid HCK). The advantages... 

Pore size optimization is one area where developmental efforts have been focused. Unimodal pore (NiMo) catalysts were found highly active for asphaltene conversion from resids but a large formation of coke-like sediments. Meanwhile, a macroporous catalyst showed lower activity but almost no sediments. The decrease of pore size increases the molecular weight of the asphaltenes in the hydrocracked product. An effective catalyst for VR is that for which average pores size and pore size distribution, and active phase distribution have been optimized. Therefore, the pore size distribution must be wide and contain predominantly meso-pores, but along with some micro- and macro-pores. However, the asphaltene conversion phase has to be localized in the larger pores to avoid sediment formation [134],... 

In this series of experiments, the catalysts were used over five repeat contacts with fresh coal liquid. Point of Ayr coal liquid was supplied by the British Coal Corporation, Coal Research Establishment (CF ) one batch of this coal liquid was used in experiments with CoMo and NiMo catalysts and a further batch was used in experiments with ZnMo and ZnW. The catalysts were prepared as extrudates by the technique of incipient wetness which requires stirring the dry alumina support with a set volume of a pre-determined concentration of an appropriate soluble salt of the metal such that the pore space is just taken up by the metals at the required concentration. The alumina support was supplied by Akzo Chemie, The Netherlands and the catalysts were made up to contain 15% WO3 or M0O3 and 3% NiO, CoO, or ZnO, expressed as a weight percentage of the weight of support... 

Fig. 6. Pseudo-first-order plots of some sulfur compounds. Reaction conditions 360°C, 2.9 MPa, NiMo catalyst. Reprinted with permission from Ref. 14, Ma etal. (1994). Copyright 1994 American Chemical Society.

HDN as applied to coal liquefaction can be performed either during the liquefaction process itself or by hydrotreatment of the released oil. In H-Coal and Synthoil processes4 19,68d the coal is directly in contact with CoMo or NiMo catalysts in the H-Coal process, a slurry of H2, coal, ex-coal oil, and... 

A set of coked NiMo catalysts has been obtained by varying the length of the time on stream from 6 h to 240 h (symbol TS), Before recovering a used catalyst, the unit was washed by gasoil at 250°C for 24 h. 

The used catalysts were washed with toluene in a Soxhlet extractor, stored in purified toluene and dried before analysis. C, H, S and N elemental analysis were performed by combustion using a Carlo Erba apparatus. The coke content is therefore defined in this work as being the carbon content of a used catalyst washed by hot toluene. Metal contents were measured by X-ray fluorescence spectroscopy. The coke hydrogen content was determined by difference between the hydrogen content measured for the used catalyst and the hydrogen content measured for the fresh NiMo catalyst (0.6 wt %). 

A commercial NiMo catalyst (Topsoe TK 771) containing 3.4% NiO, 14,3% MoO and 2% P supported on an alumina carrier was used in this study. Tests were also conducted on the unimpregnated carrier. 

The coke precursor chosen was pyrene. As shown in Fig. 6, it was found that the amount of coke deposited on a NiMo catalyst increased, at first rapidly and later more slowly, to about 14% after 150 hours. Adding DBT to the pyrene feed did not affect the rate of coking, whereas indole in the feed changed the rate and extent of coking significantly, which is not surprising in the light of the results obtained in the initial adsorption experiments. 

Figure 2. HYD activity of NiMo catalysts reported on a weight of active metals basis.

Coulier, L., V. H. J. de Beer, J. A. R. van Veen, and J W. Niemantsverdriet, Correlation between Hydrodesulfurization Activity and Order of Ni and Mo Sulfidation in Planar Silica-Supported NiMo Catalysts the Influence of Chelating Agents , J. Catal 197, Issue 1,1 January 2001, pp 26-33. 

Hydroprocesstng reactions were carried out in a SOO-mL batch reactor. The reactor is charged with 4 g of a commercial sulfided NiMo catalyst, supplied by Haldor Topsoe, Inc. and Criterion Caulysts, and 40 g of tall oil rosin (Unitol NCY), supplied by Arizona Chemical. The reactor is first purged witii Nitrogen and then filled with... 

In a previous study, we have evaluated physical properties and catalytic activites for a NiMo catalyst coked with anthracene (1). In the present study, we present similar data from a study in which the same catalyst Is coked with vacuum gas oil, and compare the results of the two sets of data. 

After adding 1 to 10 ppm H2S to the feed, both Ni and NiMo catalysts deactivate in time, although not at the same rate. In all cases the catalysts become completely deactivated, which means that the Ni based systems show almost no thiotolerance for H2S concentrations above 1 ppm. However, an important increase was noticed in the thioresistance of Mo-modified catalysts, such as is shown in Table 2, where the value of is considerably higher than that of the mcmometallic systems. 

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