| The bitumen derived heavy gas oil contains large amounts of basic and non-basic nitrogen and sulfur compounds. The presence of these contaminants in heavy gas oil creates problems not only in down stream processing such as hydrocracking and catalytic cracking of these feed stocks, but also in meeting the stringent emission specifications. These contaminants also inhibit the activities of traditional CoMo/Al2O3 and NiMo/Al 2O3 catalysts during hydrotreating of this feed. Therefore, the purpose of this research is to formulate catalysts with the incorporation of B and P with improved hydrotreating activity, quantification of surface morphology of these catalysts, and finally, correlating the morphology with the catalyst activity. The experimental plans included (a) hydrodenitrogenation (HDN) study of model nitrogen compounds using commercial catalysts, (b) catalyst preparation, characterization and initial screening using heavy gas oil, (c) catalyst stability and post reaction characterization studies, (d) catalyst surface structure and morphology analysis and quantification, and finally (e) simulation of surface morphology and its correlation with the catalyst activity.; Initially, a systematic study was conducted in a trickle-bed reactor using a commercial NiMo/Al2O3 catalyst to investigate the effects of different variables such as H2S concentration in the feed, reaction pressure (7.6–9.7 MPa), temperature (355–400°C), liquid hourly space velocity (LHSV) (0.5–2 h−1) and H2/feed ratio (200–800 mL/mL) on the HDN of typical basic (acridine) and non-basic (carbazole and 9-ethylcarbazole) nitrogen compounds present in heavy gas oil. The HDN conversion of basic nitrogen was higher than that of non-basic ones at all butanethiol concentrations (0–4 wt.%) in the feed. The present studies showed no steric hindrance effect of the alkyl group present in 9-ethylcarbazole.; Seven nickel-molybdenum, five nickel-molybdenum-boron and one nickel-molybdenum-phosphorus catalyst were prepared by incipient wetness impregnation method. Calcination temperature, nickel, molybdenum and boron (B) concentrations in γ-Al 2O3 were varied from 450 to 600°C, 1.8 to 3.1 wt%, 10.6 to 13.2 wt% and 0.5 to 1.7 wt%, respectively. Nickel-molybdenum-phosphorus catalyst contained 2.7 wt% phosphorus (P). All catalysts were characterized extensively. In these catalysts, the molybdenum oxides were present predominantly as polymolybdate and tetrahedral form. (Abstract shortened by UMI.)... |
