Upgrading Athabasca bitumen using submicronic niwmo catalysts at conditions near to in-reservoir operation

Abstract

The increasing demand for superior conversion of heavy oils and bitumen to generate high quality petroleum products requires that more efficient upgrading technologies, processes and catalysts be improved. Dispersed catalysts to enhance catalytic activity by increasing the available surface area for reaction can be implemented for in-situ upgrading where these catalysts could navigate along with the oil being produced with increased reaction time. This thesis relates to NiWMo sub-micrometric catalysts based on emulsified metallic aqueous solutions that are tested for the hydrocracking activity in the processing of Athabasca bitumen. Experiments were performed in a batch autoclave reactor of 100 ml capacity, at a total hydrogen pressure of 3.45 MPa, temperatures from 320 up to 380 °C, stirring speed of 500 rpm and reaction times varying from 3 to 70 hours. Feedstock and products were characterized using standard analytical techniques to evaluate conversion of the bitumen and product quality by assessing, viscosity, microcarbon residue, sulfur content as well as incorporation of hydrogen, among others. Main results indicated that the submicronic catalysts enhance the upgrading of Athabasca bitumen by effectively hydrogenating the liquid product thus helping to reduce coke formation and to improve viscosity and API gravity. The core reaction mechanism is thermal cracking with hydrogen superimposed following a reaction order, n= 1, and an apparent activation energy of 200 kJ mol-1 . A lumped kinetic model was produced, which can be combined with a viscosity-conversion empirical correlation and serves to predict residue conversion, product distribution, and quality of the upgraded material. Main catalyst characterization was achieved by Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD). While SEM served to study the morphology and size of the catalytic particles; XRD was complementary to provide evidence that the catalysts are mainly composites of M0S2, WS2, Mo02 and Nb S2. By incorporating sand, to create conditions near to in-reservoir operation; the catalytic particles are better dispersed keeping a nanometric size , which consequently boosts activity at the same operating conditions.