Hydrocracking zinc chloride

Major work on zinc chloride catalysts for hydrogenation and hydrocracking of coal has been carried out by Zielke, Gorin, Struck and coworers at Consolidation Coal (now Conoco Coal Development Co.) (1). The emphasis there has been on a full boiling-point range of liquid product, from treatment at temperatures between 385 and 425°C and hydrogen pressures of 140 to 200 bars. 

Direct Zinc Chloride Hydrocracking of Sub-bituminous Coal and Regeneration of Spent Melt... 

The above work concentrated most of its attention on the use of zinc chloride as the molten halide and on the use of bituminous coal extract as feed to the process. Hydrocracking of the extract (1) and regeneration by a fluidized-bed combustion technique of the spent catalyst melt (2) from the process were both demonstrated in continuous bench-scale units. 

A substantial program was also previously conducted in a batch autoclave unit on the direct hydrocracking of bituminous coal (1) with zinc chloride melts, but no work was done in either batch or continuous units on regeneration of spent melts from direct hydrocracking of coal. 

The fluid-bed combustion method (2) has been chosen, however, for process development in the regeneration of spent melts from the hydrocracking of coal. In this method, from one to two parts by weight of spent melt is generated for each part of coal fed to the hydrocracking process. The carbonaceous residue, sulfur, and ammonia retained in the melt are burned out with air in a fluidized bed of inert solids. The zinc chloride is simultaneously vaporized, the ash separated from the overhead vapors, and the zinc chloride vapor is condensed as pure liquid for return to the process. 

Zinc Chloride Hydrocracking—Batch Autoclave Work. All tests were made in a 316 stainless steel, 300-ml rocking autoclave. The equipment, the product work-up, analytical and calculational procedures used are all identical to those previously described (1). A constant hydrogen partial pressure was used in each run by monitoring it with a palladium-silver alloy probe within the authoclave. The sensitivity of the probe response was increased as compared with prior work by heat treating at... 

The melt used in this work was prepared from the residue of hydrogen-donor extraction of Colstrip coal with tetralin solvent in such a way as to simulate the composition of an actual spent melt. The extraction was conducted in the continuous bench-scale unit previously described (17) at 412°C and 50 min residence time. The residue used was the solvent-free underflow from continuous settling (17) of the extractor effluent. The residue was then precarbonized to 675°C in a muffle furnace. The melts were blended to simulate the composition of a spent melt from the direct hydrocracking of the Colstrip coal by blending together in a melt pot zinc chloride, zinc sulfide, and ammonium chloride, ammonia, and the carbonized residue in appropriate proportions. Analysis of the feed melt used in this work is given in Table I. 

U. S. Dept, of the Interior. Interim Report No. 2, Research on Zinc Chloride Catalyst for Converting Coal to Gasoline—Phase I—Hydrocracking of Coal and Extract with Zinc Chloride, Vol. Ill, Book 1, March 1968. 

A bituminous coal from Utah (Table I) was used in this work. The coal oil (Table II) used was obtained from a bituminous coal by hydrogenation using zinc chloride as the catalyst in a semi-continuous reactor system. Anthracene, phenanthrene, WS9 and NIS used were pure grade chemicals of over 99% purity. H-zeolon was a synthetic mordenite cracking catalyst and was supplied by Norton Chemical Company. NIS-H-zeolon was prepared by spraying nickel on H-zeolon with a subsequent sulfiding operation. NIS-WS -SiO -A1 O. catalyst used was a commercial hydrocracking catalyst. Analyses of reactants and products were done by standard methods. 

The use of zinc chloride as a means of liquefying coal is not surprising since there has been an interest in process catalysis by Lewis acids (e.g., zinc chloride) from the very early days of coal liquefaction technology (Nowacki, 1979). The chemistry involved in the hydrocracking (and other) reactions is not fully understood and therefore any mechanistic speculations are not warranted here. 

C.W, Zielke and E. Gorin. Kinetics of Hydrocracking of Coal Extract with Molten Zinc Chloride Catalysts in Batch and Continuous Systems. lEC Proc. Des. Dev. (1969) 546. 

Studies of the thermal decomposition of polystyrene have been made in fluidized or fixed bed reactors with the aim of controlling the yield of products. " The course of the reaction may be modified by using different contact particles in a fluidized bed, by adding various halogenated compounds, or by hydrocracking in the presence of zinc chloride. ... 

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