Laboratory findings are presented for the dispersion process of water-soluble dispersed catalyst and the slurry-phased hydrocracking of Liaohe vacuum residue (LHVR). Optical microscopy was adopted to characterize the dispersion process, and the impacts of various factors on the process were studied by means of the particle size distribution (PSD) of catalysts, which was obtained from the micrographs using the Image-Pro Plus image analysis program. Effects of the dispersion on LHVR conversion and coke formation were then investigated in an autoclave simulating slurry-phase hydrocracking. The results indicated that the dispersion of catalyst is significantly improved by reducing the interfacial tension between the precursor solution and the feedstock, and the yield of lighter fraction (gas and gasoline), coke, content of asphaltene in bottom from products, and conversion of condensation reaction decrease to follow the decreasing interfacial tension. That is, higher dispersion of the catalyst could enhance the catalyst's ability to inhibit in-depth condensation and excessive cracking. Higher stirring rate could promote the dispersion of catalyst and its ability in the low range, but there is a critical stirring rate. Lowering concentration of the precursor solution is slightly conducive to improving the dispersion of catalyst and its ability, but the degree of enhancement is more minor compared with the interfacial tension.
Cephalosporin C (CPC) acylase is an enzyme which hydrolyzes CPC to 7-aminocephalosporanic acid (7-ACA) directly, and therefore has great potential in industrial application. In this study, the CPC acylase from a recombinant Escherichia coli was purified to high purity by immobilized metal affinity chromatography, and the CPC acylase was covalently attached to three kinds of epoxy supports, BB-2, ES-V-1 and LX-1000EP. The immobilized CPC acylase with LX-1000EP as the support shows the highest activity (81 U g -1 ) suggesting its potential in industrial 7-ACA production. The activity of immobilized enzyme was found to be optimal at pH between 8.5 and 9.5 and to increase with temperature elevation until 55°C. Immobilized CPC acylase showed good stability at pH between 8.0 and 9.5 and at temperature up to 40°C. To avoid product degradation, the production of 7-ACA utilizing immobilized enzyme was carried out at 25°C, pH 8.5 in a designed reactor. Under optimal reaction conditions, a very high 7-ACA yield of 96.7% was obtained within 60 min. In the results of repeated batch production of 7-ACA, 50% activity of the initial cycle was maintained after being recycled 24 times and the average conversion rate of CPC reached 98%.
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