Study On Modification Of Shenmu Semi-coke And Their Application For Photocatalytic Conversion Of CO₂

In recent years, as the country's economy slow down, semi-coke industry gradually appears the trend of overcapacity. Meanwhile, a large amount of semi-coke powder are produced in the process of semi-coke production, which is not only difficult to use, but also cause serious environmental pollution. Therefore, the new utilization of semi-coke has become a hot topic for academia and industry. On the other hand, semi-coke derived from the refining process of bitumite, which possesses high content of fixed carbon, rich oxygen containing functional groups, abundant pore structure, large specific surface area and so forth. Hence, semi-coke can be used as adsorbent and catalytic materials. Herein, in our work, we innovatively propose that semi-coke as photocatalyst are used for photocatalytic reduction of CO2, which can not only convert CO2 to high value-added chemical fuels, but also broaden utilization of semi-coke and ease environmental issue caused by semi-coke powder.(1) The effect of illumination time, dosage of semi-coke, minerals in semi-coke and other factors on the photocatalysis of CO2/H2 O to synthesize methanol were systematically studied. The results showed that: it is observed that raw semi-coke show a better photocatalytic performance, in accord with our hypothesis. The yield of methanol increases with irradiation time increases. the yield of methanol increases firstly and then decreases. When the addition of semi-coke is 1.0 g/L, the yield of methanol is up to 18.35 ?mol/g·cat under irradiation for 12 h. Minerals play a very important role in photocatalytic process and photocatalytic performance are of Shenmu semi-coke greatly reduced when it had demineralized(De-ash).(2) A series of semi-coke supported photocatalysts are successfully prepared by impregnation method and the effect of ionic species, addition, catalyst dosage and other factors on the photocatalytic CO2/H2 O to methanol are further investigated. The results shown that the photocatalytic properties of supported semi-coke are better than pure semi-coke and the performance of the photocatalytic activity is CuO-BJ>Fe2O3-BJ>NiO-BJ. The yield of product methanol firstly increases and then decreases as the load amount increase under the same conditions. The yield of product methanol is up to 41.65 ?mol/g·cat using CuO-BJ as photocatalyst under illumination for 12 h, copper is 2.0% and the catalyst dosage is 1.0 g/L, which is 2.27 times that of pure semi-coke under the same conditions.(3) The effect of actived semi-coke prepared using different activation method on the photocatalytic CO2/H2 O to methanol were investigated. The photocatalytic activity of activated semi-coke was superior to pure semi-coke. The photocatalytic performance were OH-BJ>H-BJ>BJ. The yield of product methanol is up to 24.96 ?mol/g·cat using OH-BJ as photocatalyst under illumination for 12 h and the catalyst dosage is 1.0 g/L under the same conditions.(4) The synergic effect between supported ionic and semi coke can broaden the spectral absorption range which can effectively accelerate the charge separation and transfer corrosive holes and proposed to be responsible for the enhancement of the photocatalytic activity and photostability.