Yoshikazu Sugimoto’s research while affiliated with National Institute of Advanced Industrial Science and Technology and other places

This study investigated the transfer of oxygen and hydrogen species from steam to product during the catalytic cracking of heavy oil with iron oxide-based catalysts containing zirconia and alumina. Light oil and carbon dioxide were produced in the catalytic oxidative cracking of petroleum residual oil in the presence of steam. The alkene/alkane ratio of light aliphatic hydrocarbons decreased and carbon dioxide yield increased with higher flow rate ratio of steam to feedstock. The steam catalytic cracking of dodecylbenzene as a model compound of heavy oil showed lower alkene/alkane ratio and generation of a small amount of oxygen-containing compounds. The oxygen species derived from steam reacted with heavy oil and were transferred to carbon dioxide and a small amount of oxygen-containing compounds, producing hydrogen species from the steam. The hydrogen species were transferred to light hydrocarbons, thus suppressing alkene generation. The alkene/alkane ratio decreased with higher supporting zirconia content in the catalyst because zirconia promotes hydrogen generation from steam.

This study compared various thermal cracking processes for Athabasca oil sand bitumen according to the relationship between vacuum residue (VR) conversion and the product yield for each process, using reported data. The conversion was defined as the fraction of VR that was converted to lighter products. The conventional processes examined were visbreaking, delayed coking, and fluid coking, and the developing processes were high conversion soaker cracking (HSC), heavy to light (HTL), I(Y)Q, Eureka, and supercritical water cracking (SCWC). HSC and SCWC were higher severity visbreaking-type processes with conversions of 0.49 and 0.390.50, respectively. HTL and I(Y)Q (recycle) were lower severity fluid coking-type processes with a conversion of 0.52. I(Y)Q (once through) and Eureka showed the highest conversions (0.620.68). Supercritical water (SCW) upgrading was operated experimentally at higher severity, with a conversion of 0.64, and showed the highest yield of distillate product (DP) among all thermal cracking processes investigated. Analysis of the conversionyield relationship revealed the thermal cracking behavior of Athabasca bitumen. The key for achieving higher conversions with lower coke yield was considered to be efficient mass transfer of the volatile fraction stripped away from the condensed phase, which is a liquid fraction at the experimental condition. The condensed-phase decomposition showed an upper limit of conversion of 0.55, and that with a high mass-transfer system exceeded 0.65.

The advantage of using supercritical water (SCW) as a reaction medium for bitumen upgrading was investigated through comprehensive analyses and comparisons of the products obtained using SCW or high-pressure nitrogen. SCW showed almost no chemical effect, but it showed a dispersion effect that led to intramolecular dehydrogenation of the heavier component and prevented recombination reactions. The optimal condition for maximizing this dispersion effect was estimated using the dielectric constant and Hansen solubility parameter (HSP). The necessary condition of SCW to show good miscibility with heavy oil was when the dielectric constant was >2.2 and the HSP hydrogen bonding component was <10 MPa05. The optimal conditions were confirmed by the highest extraction yield of asphaltene and the greatest yield of upgraded oil.

Bitumen was cracked in a high-pressurized water upflow at 440 °C and 10, 25, and 30 MPa using continuous stirred tank reactor. At 30 MPa, which was the optimal dispersion condition, the highest liquid yield, lowest coke, highest conversion, and heaviest liquid products were obtained. Even at optimal conditions, all the asphaltene (AS) could not be entrained with the supercritical water (SCW) upflow; thus, the product oil contained <0.5% of AS. This means that bitumen cracking in the SCW upflow was a combined process of thermal upgrading and deasphalting.

Thermal cracking of paraffinic atmospheric residue (AR) was performed in a continuous-flow reactor under the reaction conditions of 440-520 °C and N2 0.2-0.8 MPa, and the effects of the reaction temperature and pressure on the product distribution were examined. The vacuum residue fraction gradually decreased up to 480 °C and almost disappeared at higher temperatures. Accordingly, the yields of total distillate and coke increased and became nearly constant over 480 °C. As the heavy distillate yield increased over 480 °C, the yield of lighter distillates was the highest at 480 °C and decreased at higher temperature. When the reaction pressure was increased, the heavy distillate yield decreased with increasing yields of lighter distillates and coke. Two paraffinic and two Middle East ARs were thermally cracked under the conditions of 480 °C, N2 0.4 MPa and 0.5 h, and the product composition and properties were compared. The yield of distillates (C4-500 °C) was around 90 % for paraffinic ARs, and 70-80 % for Middle East ARs. The sulfur contents of the distillate products from paraffinic ARs were much lower than those of Middle East ARs, but the difference in the nitrogen contents was not significant. Pyrolyzed middle and heavy distillates were hydrotreated to investigate their hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) reactivities. The HDS rates of the distillates obtained from paraffinic ARs were 4-6 times higher than those of Middle East ARs. The HDN rates were comparable for the middle distillates, but the HDN rates of the heavy distillates from paraffinic ARs were lower than those from Middle East ARs.

Properties, chemical compositions and hydrotreatment reactivities of Mongolian crude oils and their distillation fractions were investigated and compared with those of Chinese and Middle East crudes. Mongolian crude oils were highly paraffinic with high pour point (<+17 °C) and low contents of sulfur (0.09-0.24%), vanadium (<1 ppm) and carbon residue (<4.6%), but contained large amounts of atmospheric residue (68-83%). These features are very similar to Chinese Daqing crude. The middle and heavy distillates included large amounts of saturates (>85%) and n-paraffins (35-50%). The nitrogen contents were comparable with the other crude oils or distillation fractions examined. The distillates and atmospheric residues were hydrotreated, and the reactivities of hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) were compared. The HDS rates of low-sulfur feedstocks were much larger than those of high-sulfur feedstocks derived from the Middle East, whereas the HDN rates of the same boiling range fractions were similar. The relative HDS rates of the Mongolian feeds to the corresponding mixed Middle East feed were 6-14 for the middle distillates, 7-12 for the heavy distillates, and 5-6 for the atmospheric residues, and the relative HDN rates were 1-2<, 1-2.3 and 0.6-1, respectively. Polyaromatics were readily hydrogenated to monoaromatics but not to saturates due to the difficulty in further saturation.

The desulfurization behavior of oil sand bitumen in supercritical water (SCW) was examined to evaluate the possibility of desulfurization using SCW. Athabasca bitumen was treated with water, nitrogen, or toluene at 430-450 °C and 23-30 MPa using a batch autoclave. SCW showed the same trends in sulfur content, liquid and coke yields as high-pressure nitrogen. Furthermore, liquid products obtained using SCW had the same distributions of sulfur-containing compounds as high-pressure nitrogen and showed no specific results, whereas supercritical toluene was involved in desulfurization as a reactant. However, the reaction media influenced the sulfur distribution to coke with the variations of desulfurization ratio and sulfur conversion: that using SCW was higher than using toluene and lower than using nitrogen. SCW showed dispersion effect against the desulfurization reaction, whereas toluene showed radical scavenging and dispersion effects. The dispersion of reactant enhances intramolecular dehydrogenation and keeps the product toluene-soluble rather than coke. Because SCW retained heavy fraction as liquid product than high-pressure nitrogen, the desulfurization of bitumen using SCW was not evaluated to be practically promising.

The advantages of supercritical water (SCW) as a reaction medium for upgrading oil sand bitumen were investigated through a comprehensive analysis of the output product, which includes gaseous products, middle distillate, distillation residue, and coke. Canadian oil sand bitumen mined by the steam assisted gravity drainage method was treated in an autoclave at 420–450°C and 20–30MPa for up to 120min with three kinds of reaction media: SCW, high-pressure nitrogen, and supercritical toluene. The yields of gaseous products indicated that a very small amount of water was involved in the upgrading reaction. The analytical results of the middle distillate fractions were almost the same using water and nitrogen at 450°C. The distillation residues produced in SCW had lower molecular weight distributions, lower H/C atomic ratios, higher aromaticities, and consequently more condensed structures compared to those produced in nitrogen. The coke produced using SCW also had lower H/C values and higher aromaticities. Judging from all the analytical results, the upgrading of bitumen by SCW reaction was primarily considered to be physical in nature. As a result, it is possible to highly disperse the heavy fractions by SCW. This dispersion effect of SCW led to intramolecular dehydrogenation of the heavier component and prevention of recombination reactions, and consequently gave the highest conversion.

Middle distillates obtained by pyrolysis of oil shale and oil sands bitumen were denitrogenated by complex formation with CuCl 2•2H 2O, which reduced the nitrogen contents from 9900 to 2700 wtppm and from 1300 to 700 wtppm, respectively, without any change in the sulfur contents. The original and denitrogenated oils were hydrotreated over a conventional NiMo catalyst in a fixed-bed continuous flow reactor. The pre-removal of nitrogen compounds greatly enhanced hydrodenitrogenation (HDN) and hydrodesulfurization (HDS), and the rate constants were increased by 4.9-27 for HDN and 2.8-5.4 for HDS. As a result, the nitrogen and sulfur contents of the denitrogenated oils were reduced to < 1 and < 10 wtppm, respectively, under the conditions of H 2 8 MPa, LHSV 1 hF -1 and 350°C.