Characteristics of solvent quality and catalyst in direct liquefaction of subbituminous coal

Abstract

The liquefaction characteristics of subbituminous coal were examined in a set of three microreactors. Each had a volume of 30 ml capacities. The purposes of this study can be splitted into three parts: (1) determination of the most significant process variables affecting coal liquefaction yields. For this, the experiments were carried out using two level full factorial design to elucidate the influence of qualitative variables (the nature of gas phase, solvent type and catalyst) and quanitative variables (temperature, initial total pressure and contact time) upon liquefaction yields under short contact time conditions. Analysis of variance technique was chosen to determine the significance of variables. To determine the significance of the effects, the statistical F-test with 99% confidence limits was used. (2) as a detailed experimental study of the process variables proved to be important from the above statistical experiments, firstly, the role of the solvent quality on liquefaction yields was examined by using various solvents such as non-polar hydroaromatics, non-polar aromatics, polar hydroaromatics and polar aromatics. Secondly, the importance of molecular hydrogen was investigated and the main catalytic components affecting liquefaction yields during each stage of short and longer residence time liquefaction were examined. (3) to relate liquefaction activity with catalyst acidity and catalyst physical properties, catalytic liquefaction experiments were carried out using six commercial catalysts of varying physical properties: Amocat 1A, HDN-30, HDN-60, Shell 317, Shell 324 and Amocat 1C. Also, the experiment of stepwise thermal desorption (STD) of pyridine was carried out under chromatographic conditions to measure the amount of acid and the strength distribution on each catalyst. The results obtained from these studies can be summarized as follows: From the factorial design experiments conducted to see the effectiveness of process variables in the init...