Basic Research On Composition, Structure And Efficient Conversion Of Heavy Oils

The efficient utilization of heavy petroleum becomes more and more important with rapid decrease in light petroleum resources and rapid increase in light petroleum consumption. Understanding composition of heavy oils and synthesizing new catalysts are necessary for efficient utilization of heavy oils as a basic research. For example, predicting the behaviors such as phase separation, coke formation, molecular interaction, and the cause of catalyst deactivation by understanding composition of heavy oils, and enhancing the efficiency of utilization and conversion of heavy oils by synthesizing new catalysts.Taking the consideration that composition of heavy oil is closely related to its solubility in different solvents into account, solubility of Dagang vacuum residue (DVR), Russia vacuum residue (RVR) and Kumkol vacuum residue (KVR), three kinds of heavy oils, were compared in a series of organic solvents. The extract yields of DVR, RVR and KVR are largely related to dielectric constant of the solvents, i.e., DVR, RVR and KVR tend to easily dissolve in solvents with lower dielectric constant. The compounds detected from the extraction solutions can be classified into five types: chain alkanes, cyclanes, alkenes, arenes and heteroatoms-containing compounds. Saturated hydrocarbons, i.e., chain alkanes and cyclanes are predominant with all the solvents.DVR, RVR and KVR were respectively separated in an alumina packing column by flushing with different solvents, and saturated hydrocarbon (S), aromatics (A), resins (R) and asphaltine (AT) were obtained. SARA were analyzed with GC/MS. The results show that the contents of S in KVR is more than those in DVR and RVR, and the contents of A and R in DVR is the most, and the contents of AT in RVR is more than those in DVR and KVR. The compounds detected from SARA of DVR, RVR and KVR consist of chain alkanes, cyclopanes, alkenes, arene and heteroatoms-containing compounds. DVR, RVR and KVR were extracted in Soxhlet extractor with petroleum ether (PE), benzene and carbon disulfide (CS2) sequentially and the extracts were analyzed with GC/MS. The results show that group components of organic compounds in DVR, RVR and KVR can be separated preferably by fractional extration. The compounds detected from the first PE extracts mostly consist of normal chain alkanes (C10-C43), branched alkanes (C16-C28), cyclanes (C24-C36) and alkenes (C11-C30). The compounds detected from the second PE extracts mostly consist of alkyl phenyl carbonic acid esters. The compounds detected from the first benzene extracts are different from those in the second benzene extracts. Moreover, hydroquinone from DVR, ditertbutylparacresol from RVR, and biphenyl from KVR in benzene extracts are predominant. However, any compounds weren't dedtected in CS2 extracts. The solubilization behavior of long-chain alkenes was investigated during the fractional extraction. The results show that long-chain alkenes have stronger interaction with vacuum residue macromolecular or linked network structure than long-chain alkanes and are often dissolved out together with long-chain alkanes with odd carbon number.The PE-insoluble fraction of DVR (DVR-PEIF) was subject to catalytic hydrogenation in the presence of activated carbon (AC), zeolite Y (HY) and nickel (Ni) under initial hydrogen pressure of 5 MPa at 300 oC, respectively. Most of compounds detected with GC/MS in the PE-soluble fraction of products from DVR-PEIF are aliphatic species. Small amounts of arenes and heteroatom-containing compounds were also identified. The results show that the AC and Ni catalyzed the catalytic cracking and the catalytic hydrogenation of DVR-PEIF, respectively.Hollow zeolite structures including sodalite spheres and hollow zeolite NaA crystals were synthesized by introducing crosslinked polyacrylamide (C-PAM) hydrogels into zeolite synthesisgels. The synthesis gels with weight compositions of 0.8SiO2: 1.0Al2O3: 21.2Na2O: 86.0H2O: 7.4-28.7 acrylamide (AM) were used to produce hollow sodalite spheres. The synthesized hollow sodalite spheres had diameter of 1-5μm and shell thickness of 0.5-1μm, and the sphere diameters decreased from 5-10μm to 1-3μm as the amount of C-PAM increased. Hollow zeolite A crystals with sizes of 300-500 nm were grown from the synthesis gel with a weight ratio of 0.8SiO2:1.0Al2O3: 2.6Na2O: 16.4H2O: 2.6-3.8AM. The experimental results suggest that the formation of hollow zeolite structures may involve a surface-to-core crystallization process induced by crosslinked polyacrylamide networks.