The large amount of waste gas containing volatile organic compounds (VOCs) discharged from petrochemical sewage plants will cause air pollution and seriously endanger the safety of human beings and the ecological environment. In this paper, we proposed a photocatalytic oxidation degradation technique of VOCs and designed a photocatalytic reaction device loaded with TiO2/SnO2 catalyst. Under UV light irradiation, there is an energy level difference in the conduction band between TiO2 and SnO2, which makes the photogenerated electrons (e–) migrate to SnO2 and reduces the surface electron density of TiO2. Thus, the recombination of photogenerated electron–hole pairs (e––h+) is inhibited and the catalyst activity is improved. Meanwhile, the synergistic effect of the oxidation of hydroxyl radicals (·OH) and ozone greatly improves the conversion rate. In addition, in the industrial side line, by studying the influence of inlet gas volume, inlet gas concentration, and gas humidity (RH) on the conversion rate of the VOCs, we revealed the operation law of the photocatalytic technique in industrial applications. Under the best working conditions, the purification rate of the VOCs was as high as 92.73%. This technique can not only effectively avoid the damage to the environment caused by polluting VOCs but also promote the low-carbon and green development of enterprises in the industry.
Jiaqi Yan,Jingxuan Zhao,Jing Guo,Zhiyong Yang,Mingjun Xiong,Langsheng Pan,Yongfei Li
The self-aldol condensation of cyclopentanone (CP) to aviation fuel precursors was studied over various acid-base bifunctional TiO 2 -based catalysts. Combining TiO 2 and SnO 2 improved the catalytic performance and reduced the apparent activation energy, resulting in a selectivity of 97.5 % for 2-cyclopentylidene cyclopentanone (dimer C 10 ) and 2,5-dicyclopentylidene cyclopentanone (trimer C 15 ) (with 79.2 % yield for dimer C 10 ) at a CP conversion of 92.5 %. Response surface methodology (RSM) analysis of the reaction parameters showed that the actual results were in considerable concordance with the predicted ones. The excellent catalytic performance and stability exhibited by the TiO 2 -SnO 2 nanocomposites catalyst were attributed to (i) the nanoscale mixed metal oxide grains (bonded by Ti–O–Sn) and highly dispersed active Ti δ+ species, which facilitated the adsorption and activation of CP; (ii) the increase in surface O C species contributing to the abundance of hydroxyl groups (including M δ+ –O – pairs), which promoted the formation of the enolate intermediates; (iii) the construction of appropriate medium acid-base sites and the Brønsted/Lewis acid sites (BAS/LAS) ratio, which favored the formation of the desired dimer C 10 . Conversely, the TiO 2 -SiO 2 catalyst with plentiful strong acid-base sites induced the successive condensation of CP, which favored the formation of trimer C 15 . Furthermore, a plausible reaction mechanism for the catalytic self-aldol condensation of CP over the TiO 2 -SnO 2 catalyst was proposed. This study developed an efficient and stable TiO 2 -SnO 2 catalyst for CP self-aldol condensation with promising application potential.
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