Characterization of Ni/AlMCM-41 Catalysts and Their Catalytic Performance in n-Dodecane Hydroconversion

A series of Ni/AlMCM-41 catalysts with different nickel contents was prepared via the incipient wetness impregnation method. The effects of the nickel content on the structure, acidity and metal function of the catalysts were studied by using different techniques. In the test of n-dodecane hydroconversion, it was found that the metal and acid functions were well balanced over a 2.0%Ni(mass fraction)/AlMCM-41 catalyst, which gave the maximal isomerization selectivity and a homolytic cleavage products.

Study on the Effect of Catalyst Properties on Residue Hydroconversion

The effect of catalyst properties on residue oil hydroconversion was studied at moderate operating conditions(at a temperature of 400 ℃, an initial hydrogen pressure of 10 MPa, and a reaction time of 4 h) in a batch mode slurry phase with different catalyst samples. The results showed that the catalyst acidity had a good effect on residue conversion and MCR(micro carbon residue) conversion but brought about higher coke yield. Residue conversion was thermally induced but the catalyst acidity changed its conversion route. A catalyst with higher metal loading, higher hydrogenation activity and appropriate pore size had higher sulfur and metal removal rate, higher MCR conversion and also a lower coke formation. The activity of spent commercial catalyst AS1 and DS1 was slightly lower than the corresponding fresh ones but was still high enough for residue oil hydroconversion. It assumes that the role of the catalyst is to activate hydrogen species toward reaction with an aromatic carbon radical to yield a cyclohexadienyl type intermediate which will turn into liquid and also to absorb the mesophase which can easily aggregate to form coke.

n-Dodecane Hydroconversion over Nickel Supported on Different Mesoporous Aluminosilicates

Several 2.0 wt% nickel catalysts supported on nanometer bimodal mesoporous aluminosilicate (NBMAS), AlHMS and AlMCM-41 were prepared by means of the wetness impregnation method. The characterization tech-niques such as Py-FTIR and H2 chemisorption showed that the amount of Br鰊sted acid sites decreased in the order of Ni/AlHMS>Ni/AlMCM-41>Ni/NBMAS, while the nickel dispersion differed a little. In the catalytic n-dodecane hydroconversion, the highest conversion was obtained over Ni/NBMAS, and the lowest isomerization selectivity occurred over Ni/AlHMS. For the cracked products, the symmetrical carbon number distribution cen-tered at C6 was obtained on the Ni/AlMCM-41 catalyst due to the well balanced metal/acid functions, whereas the Ni/AlHMS and Ni/NBMAS catalysts led to more C3-C5 and C1+C11 products, respectively.

Analyzing the energy intensity and greenhouse gas emission of Canadian oil sands crude upgrading through process modeling and simulation

This paper presents an evaluation of the energy intensity and related greenhouse gas/CO2 emissions of integrated oil sands crude upgrading processes. Two major oil sands crude upgrading schemes currently used in Canadian oil sands operations were investigated： cokingbased and hydroconversion-based. The analysis, which was based on a robust process model of the entire process, was constructed in Aspen HYSYS and calibrated with representative data. Simulations were conducted for the two upgrading schemes in order to generate a detailed inventory of the required energy and utility inputs： process fuel, steam, hydrogen and power. It was concluded that while hydroconversion-based scheme yields considerably higher amount of synthetic crude oil （SCO） than the cokerbased scheme （94 wt-% vs. 76 wt-%）, it consumes more energy and is therefore more CO2-intensive （413.2kg CO2/m3sco vs. 216.4kg CO2/m^3sco）. This substantial difference results from the large amount of hydrogen consumed in the ebullated-bed hydroconverter in the hydroconversion-based scheme, as hydrogen production through conventional methane steam reforming is highly energy-intensive and therefore the major source of CO2 emission. Further simulations indicated that optimization of hydroconverter operating variables had only a minor effect on the overall CO2 emission due to the complex trade-off effect between energy inputs.