Catalytic cracking of Asphalt Ridge bitumen

Theoretical considerations of the molecular structure of Uinta Basin, Utah tar sand bitumen, viz. high-molecularweight naphthenic hydrocarbons, suggest potential for direct catalytic cracking of these materials. Preliminary results show that virgin bitumen is responsive to catalytic cracking but that the efficiency of an 82 A pore diameter catalyst is low owing to either exclusion of molecules or adsorption of nonvolatil molecules at the catalyst pore mouth, or both. Typical yields at 460°-500° C and 2:1 cat-to-oil ratio are 7 wt % gas, 80 wt % liquids, and 13 wt % coke. Liquid products typically are comprised of 66% saturated hydrocarbons and 34% aromatic and polar molecules. The gasolines produced exhibit low octane numbers resulting from competing thermal reactions under the conditions studied. An increase in cat-to-oil ratio results in a dramatic increase in gasoline yield and a significant increase in coke yield at the expense of medium and low volatility liquids. Catalytic activity improves notably when visbroken, deasphalted, or hydropyrolyzed bitumen is used as the feedstock. For the latter case, in which 2.6 wt % hydrogen is added during hydropyrolysis, yields are 30% gases, 64% liquids, and 6% coke, based on the virgin bitumen.