Nand K. Narain

Large-pore NiMoAl2O3 catalysts for coal-liquids upgrading☆

Abstract A novel method that can produce large-pore unimodal or bimodal alumina extradates was developed. Since the method used to produce the larger-diameter pores does not involve a steaming or sintering process, the resultant supports have high surface areas, ~350 m 2 /g. Also, the technique allows catalysts with widely varying pore structures to be prepared while holding all preparation variables constant except for the extent of mixing used during preparation of the extrusion batch. These experimental supports were used to prepare NiMo catalysts for upgrading coal liquids. The results of an initial batch-screening test suggest that the resulting bimodal catalysts are more effective for upgrading coal liquids than the corresponding unimodal catalysts.

Catalytic hydrotreatment of coal-derived residua

Abstract An investigation was conducted to determine the activities of various coal-liquefaction residua during catalytic hydrotreatment. Residua produced at low- and high-severity coal-liquefaction conditions were employed, as well as a nondeashed residuum produced at low-severity conditions. All experimental runs were performed in a continuous-flow hydrotreating unit using Shell 324M catalyst. Except for hydrogenation activity, catalyst activity declined with a typical S-shaped deactivation curve. The properties of the spent catalysts do not depend significantly upon prior processing of the feedstock; however, the prior processing history of the feedstocks affected their reactivity and the rate of catalyst deactivation. The results indicate beneficial effects of conducting coal liquefaction at low-severity conditions and of product deashing prior to catalytic hydrotreatment.

Incorporation of quinoline into coal and coal-derived products

Quinoline forms an adduct with Bruceton hvAb coal at temperatures < 250 °C in the absence of H2 pressure and catalyst. The extent of quinoline incorporation into Bruceton coal was both time and temperature dependent. After 4 h at 200 °C, ≈ 20 wt% of quinoline had incorporated into the coal, as indicated by solubility measurements. A dissolution-precipitation technique was employed to permit a clean separation of physically-entrapped quinoline from the crude adduct. The crude adduct isolated in the first precipitation step had ≈ 75% of its quinoline content physically entrapped and 25% chemically bound, presumably by hydrogen bonding to acidic centres.

Effects of solvent pretreatment and solvent incorporation on coal liquefaction

Abstract Yields of short-contact-time liquefaction product can be increased by pretreating the coal-solvent slurry at below normal liquefaction temperatures to permit solvent incorporation and/or swelling of the coal before liquefaction. An external pretreatment and an in situ pretreatment produce similar results. A coal-vehicle adduct was isolated from the pretreated coal and had liquefaction characteristics similar to the original coal. The beneficial effect of the solvent pretreatment is therefore believed to be the result of physical solvent incorporation with the coal, which causes solvent-aided liquefaction, in contrast with the thermal decomposition that can occur if some of the coal reaches liquefaction temperatures before it is contacted by vehicle. Pretreatment allows vehicle to be present (in contact with coal) at the reactive site in order to react with, and cap, coal free radicals.

Hydroprocessing of nondeashed coal-derived residuum: Evaluation of catalyst performance

Abstract Four commercially available catalysts were evaluated for 100 hours in a continuous-flow unit to determine their effectiveness in the hydrotreating of nondeashed coal-derived residuum. These included Shell 324M and Shell 424 (both unimodal), and Shell 317 and Amocat 1C (both bimodal). All catalysts contained nickel and molybdenum supported on alumina; compositions were, however, different. The results showed that all catalysts performed equally well, except that the desulfurization activity of Shell 424 was substantially higher than the activities of the other catalysts. The bimodal catalysts accumulated more carbonaceous material and trace metals than the unimodal catalysts. Also, their catalytic activity was similar to the activities of the unimodal catalysts.

Gas chromatographic estimation of malathion in seven vegetables

Abstract A simple and rapid gas Chromatographic method was developed to determine the residue levels in the vegetables. This method proved to be accurate and reliable for total residue estimation, giving recoveries of 90–94% with exception of tomato, from fortified vegetable samples. Residues level on these vegetables sprayed with malathion (2.7 1b ai/acre) were well below the tolerance limit of 8 ppm established by EPA.