Bitumen partial upgrading over Mo/ZSM-5 under methane environment: Methane participation investigation

摘要

Bitumen extracted from oil sands which is abundant in Canada needs to be partially upgraded in order to meet pipeline specifications before being sent to downstream refineries. Hydrotreating where expensive hydrogen is involved at high pressure (15 similar to 20 MPa) is commonly employed as the technique to satisfy the upgrading requirement. In this study it is reported that a partially upgraded crude oil can be readily produced from bitumen under methane environment at mild conditions (400 degrees C and 3 MPa) without H-2 engagement under the facilitation of 5%Mo/ZSM-5 (SiO2/Al2O3 = 23:1). The methane participation into the upgrading process was evidenced by analyzing the products obtained from the methanotreating of styrene and n-butylbenzene, the model compounds to represent heavy oil, as well as the heat effect during upgrading. Direct evidence of methane incorporation into the product molecules is observed on H-1, D-2 and C-13 NMR spectra, revealing that the carbon and hydrogen from methane occupy the phenyl carbon sites and aromatic and benzylic hydrogen sites, respectively, in the product molecules. Through extensive catalyst characterizations using TEM, XRD, and XPS, the excellent catalytic upgrading performance might be closely related to the highly dispersed molybdenum oxide particles on the zeolite support at partially reduced oxidation state for better methane activation. The outcomes from this research could not only create an innovative route for more profitable natural gas utilization, but also benefit bitumen partial upgrading in a more economical and environmentally friendly way. (C) 2016 Elsevier B.V. All rights reserved.