雙胞反應器進行光催化降解苯酚同時分離生產氫氣

氫氣是一種良好的能量載體，以光催化水分解的方式製備氫氣是一種極具發展前景的技術；苯酚是一種廣泛存在於工業廢水中的，對自然環境和人類健康都有破壞性的有機污染物質，光催化氧化是能夠有效去除苯酚污染的一種高級氧化技術。已有研究指出，可以將上述兩個反應結合，利用光催化技術同時氧化苯酚並還原水產氫氣，達到獲得清潔能源氫氣的同時去除有機污染物的目的，被稱作雙功反應，但產物氫氣和CO2是混合在一起的。本研究利用高溫固態法搭配光沉積法製備Pt/STO:Rh作為產氫觸媒，以商購WO3作為苯酚氧化觸媒，搭配Fe3+/Fe2+離子對作為電子傳輸介質，在300 W Xe燈光照下於單一混合型反應器中進行苯酚降解同步生產氫氣的雙功反應，發現氫氣8小時產量為5.59 μmol/g，同時苯酚降解率達到13% (初始濃度200 μmol/L)，降解產物以CO2為主。使用雙胞膜分離式反應器，將兩種觸媒以Nafion膜分開於反應器兩端，減少觸媒間的遮蔽效應和對光的競爭吸收，與使用單一混合式反應器相比，可提升產氫和苯酚降解之效率，6小時氫氣產量為11.37 μmol/g，苯酚降解率達到22%。同時，利用雙胞反應器，產氫反應和苯酚氧化反應於兩端發生，當苯酚初始濃度為200 μmol/L時，產物中86.2%的CO和87.6%的CO2與H2實現同時分離。本研究還考察了苯酚初始濃度對氫氣產量之影響，發現在50-200 μmol/L時，氫氣產量均高於相同條件下純水分解的氫氣產量(9.94 μmol/g)，且會隨苯酚濃度升高而增加，苯酚初始濃度為200 μmol/L時產量最大，與相同條件純水分解氫氣產量相比，提高20%，證實苯酚氧化反應有助於純水分解產氫。

關鍵字

光催化；水分解；產氫技術；苯酚降解；雙胞光反應器

並列摘要

Since H2 is a good energy carrier, photocatalytic water splitting and hydrogen production are promising technologies to provide renewable energy. Phenol is a kind of organic pollutants widely existed in industrial wastewater which has negative effect on environment and human health. As one of the advanced oxidation process, photocatalytic phenol oxidation is an efficient way to remove the phenol contaminant. Some researches coupled the two process above together, conducting the oxidation of phenol and reduction of H2O simultaneously. In this way, hydrogen is produced and phenol is degraded at the same time, which is a kind of dual-function reaction; however, the produced hydrogen was mixed with CO and CO2. In this research, Pt/STO:Rh was synthesized as hydrogen evolution photocatalyst by solid-state reaction method and photo-deposition method, and commercial WO3 was utilized as phenol oxidation photocatalyst. With the help of Fe3+/Fe2+ ions pair as electron mediators and the irradiation of 300 W Xe lamp, dual function reaction with initial phenol concentration of 200 μmol/L was conducted in a single batch reactor. The yield of hydrogen was 5.59 μmol/g at the 8th hour, and 13% of the phenol was removed, with CO2 as the main oxidation product. After that, the dual function reaction was conducted in a Twin reactor with a Nafion-117 membrane separating the two kinds of photocatalysts into different parts. Therefore, the shielding effect and competitive adsorption of light source were avoided and photocatalytic efficiency was raised. The yield of hydrogen is 11.37 μmol/g at the 6th hour, and the phenol removal is raised up to 22%. By the separation effect of Nafion membrane, 86.2% of the CO and 87.6% of the CO2 was simultaneously separated from hydrogen, decreasing the further cost of purification. Effect of phenol initial concentration (50 μmol/L to 200 μmol/L) on hydrogen evolution amount was investigated, and the results showed that with more phenol added, the hydrogen yield was raised. And the optimum phenol concentration is 200 μmol/L, which is 20% better than hydrogen yield of pure water splitting (9.94 μmol/g) under the same experiment conditions. Our study proved that the H2 production from water splitting can be significant enhanced via the oxidation of phenol.

並列關鍵字

photocatalysis ； water splitting ； hydrogen evolution technology ； phenol degradation ； twin photo reactor

參考文獻

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2. A. Kudo and Y. Miseki, Heterogeneous photocatalyst materials for water splitting. Chemical Society Reviews, 38 (2009) 253-278.

3. K. Maeda and K. Domen, Photocatalytic Water Splitting: Recent Progress and Future Challenges. Journal of Physical Chemistry Letters, 1 (2010) 2655-2661.

5. C. C. Lo, C. W. Huang, C. H. Liao and J. C. S. Wu, Novel twin reactor for separate evolution of hydrogen and oxygen in photocatalytic water splitting. International Journal of Hydrogen Energy, 35 (2010) 1523-1529.

6. S. C. Yu, C. W. Huang, C. H. Liao, J. C. S. Wu, S. T. Chang and K. H. Chen, A novel membrane reactor for separating hydrogen and oxygen in photocatalytic water splitting. Journal of Membrane Science, 382 (2011) 291-299.

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雙胞反應器進行光催化降解苯酚同時分離生產氫氣

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