The Study On Preparation Of Spherical Activated Carbon Based On Coal Tar Pitch From Coal Poly- Generation

Zhejiang University had put forward the comprehensive utilization program of heat, electricity, gas and tar based on coal poly-generation, to solve the problem of coal clean utilization. This program combines the coal medium-temperature pyrolysis and coal combustion, and it has a high yield of coal tar oil, in which the coal tar pitch takes 50% part of quality. Solving the utilization program of coal tar pitch would perfect the products utilization of coal poly-generation and improve the economic efficiency of poly-generation system and added value. This paper had researched several process program for preparation of spherical activated carbon based on coal tar pitch and had gotten the spherical activated carbon with high BET value and good morphology.The raw material of research is the coal tar pitch based on bituminous poly-generation under typical test conditions, of which the test device is 1MW coal poly-generation system. Limited by the process level, the pitch is with high ash content and high oxidation degree. So, when the naphthalene addition is 30%wt, the soft point of raw pitch has decreased to 110℃. But its high ash content and high oxidation degree impede the balling process. On the contrary, the high soft point pitch with low ash content has good balling property in water-based suspension after 30%wt naphthalene addition.Learning from the preparation of nano carbon powder from pitch coke, this paper had put forward a process to prepare nano-scale spherical activated carbon from aqua mesophase pitch, which gotten from reaction between raw material pitch and nitric and sulfuric mixed acid. The experiment showed that this process can remove the ash content in raw material and the nano-scale spherical activated carbon with 1500m2/g BET value. This process had offered a feasible way to deal with pitch that had low quality.On the other hand, this paper adopted the spherical pitch from medium-temperature pyrolysis as the research material, innovatively put forward the process of methylbenzene impregnation for spherical pitch to prepare conventional spherical activated carbon. Firstly, medium-temperature pyrolysis spherical pitch has been product on large-scale, that offer the probability of conventional spherical activated carbon large-scale product. Secondly, the experiments have showed that the spherical pitch with methylbenzene impregnation treatment has a good oxidation efficiency under air oxidation. That enhance the thermosetting of spherical pitch, and had gotten conventional spherical activated carbon with relatively high mesopore ratio and good sphericity. As for this process, this paper had researched the methylbenzene impregnation mechanism, such as the time, ratio of methylbenzene and spherical pitch. For the future industrial application, the industrial process has been designed in this paper and it has an excellent economic.Also, this paper had applied the nano-scale spherical activated carbon to absorb some VOCs and CO2, compared the absorption properties of nano-scale spherical activated carbon and coconut shell activated carbon. The experiments showed that the nano-scale spherical activated carbon has a better absorption property than coconut shell activated carbon. And the CO2 absorption property of nano-scale spherical activated carbon has reached a high level in this field, with 6.68wt% absorption efficiency.