Novel Mesoporous Catalysts for Vacuum Residue Hydrocracking

摘要

Crude oil will continue to be an essential primary energy source during this century. The decline in light crude oil has increased the share of heavy oils in the crude slate fed to refineries. The development of new catalysts that can withstand deactivation by heavy feeds can be readily applied in industry. The aims of this work centred in the development and characterisation of novel NiMo mesoporous catalysts along the testing of such materials in hydrocracking reactions using a heavy hydrocarbon feed, Maya vacuum residue (VR). Four categories of catalytic supports were synthesised: mesoporous alumina (Al2O3), mesoporous alumina doped with Cr (Al2O3-Cr), mesoporous silica alumina (MSA) and carbon nanofibres (CNF). An experimental method was developed for one hour hydrocracking reactions between 400 and 450 °C in a batch reactor using VR. Selected catalysts were utilised in a second reaction with fresh feed. The catalysts short term deactivation was investigated and related to the product distribution and reaction conditions.udIt was found that reaction temperature had an important impact on conversions and product distributions. The conversion of materials with a boiling point above 450 °C was mainly thermally driven. NiMo catalysts supported on Al2O3, Al2O3-Cr and CNF led to high asphaltene conversions without suffering significant deactivation. On the other hand, the MSA supported catalyst was active mainly due to thermal reactions and its pores were blocked by coke deposits by the first hour of reaction. The Al2O3-Cr support allowed not only higher NiMo dispersion than Al2O3, but also better dispersion of the coke deposits after reaction. NiMo catalysts supported on CNF showed they could be very active in VR hydroprocessing, depending on their synthesis conditions.