Pyrolysis of Utah tar sands: products and kinetics

Abstract

The development of successful in-situ thermal recovery techniques for the Utah tar sands requires a knowledge and consideration of the pyrolytic behavior of these bituminous materials. Tar sands from four major Utah deposits, Northwest Asphalt Ridge, Tar Sand Triangle, P.R. Spring, Sunnyside, and from one Canadian deposit, Athabasca, were subjected to pyrolysis, in an inert atmosphere, at temperatures ranging from 500/sup 0/ to 1000/sup 0/F. All tar sand material was studied in the native state, no prior extraction or separation of the bitumen from the sand being performed. Pyrolysis products, i.e., oil, coke, and gas, were quantified and examined. Data for the thermal decomposition of tar sand bitumen followed first-order kinetics in the range of 700 to 1000/sup 0/F. The rate constants and activation energies for the pyrolysis of these materials are essentially independent of tar sand source, ranging from approximately 1 x 10/sup -4/ sec/sup 1/ at 700/sup 0/F to approximately 200 x 10/sup -4/ sec/sup -1/ at 1000/sup 0/F, with activation energies of approximately 30 to 35 kcal.