Heavy oil and bitumen extracted from oil sands such as the ones abundant in Canada cannot be directly sent to existing refineries mainly due to its high viscosity. Traditionally, thermal cracking is widely employed to break down the long carbon chain to lower the viscosity. However, such treatment results in higher content of unsaturated light olefins which will create implementation issues such as carbon deposition during storage and transportation and incomplete combustion and generate negative environmental impact. Therefore, hydrotreating is an important process to saturate olefins, which consumes expensive hydrogen and requires extremely high operating pressure. Replacing hydrogen with natural gas and lowering the operating pressure would decrease the cost of oil refining. In the present work, methane, the main component of natural gas, is activated with novel zeolites based nanoporous catalysts loaded with active metals and saturate the olefins at low pressure. Several representative model compounds including 1-octane, 1-decene, n-butylbenzene and styrene are employed to analog the unsaturated components in cracking products of heavy oil. The saturation are carried out along with catalyst and methane with significantly decreased pressures compared with hydrotreating process, i.e. 10 bar and 30 bar. The saturation of model compounds undergo a series of reaction, involving catalytic cleavage of C-H bonds and addition of CHx and H into unsaturated bonds. The study of the reaction mechanism is executed from multiple aspects with several analytic instruments, including the GC-MS analysis of products, which provides the composition information, and Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS), which detects the formation of organic species. 13C and 2D enriched methane are also employed to track the catalytic pathways. Several key products such as ethylbenzene, propylbenzene, isopropylbenzene and butylbenzene, which are the saturation products of styrene, are separated and purified. Their 1H NMR, 13C NMR, FTIR and GC-MS spectra reveal how the CHx and H are added into unsaturated bonds. This work clearly demonstrates the feasibility of upgrading the olefin-rich petroleum by directly using cheap natural gas on zeolite-supported catalyst at moderate pressure. This mechanistic study would also benefit the rational design of catalyst for direct upgrading of heavy crude oil using natural gas in the future.

Catalytic light olefin upgrading: Using natural gas for gasoline quality improvement

249th National Meeting (2015)

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