Cu/ZSM-5觸媒在二氧化碳光催化還原之應用

Abstract

本研究旨在探討自行製備的Cu/ZSM-5觸媒，進行光催化還原二氧化碳之批次反應研究，並進一步探討不同觸媒條件下對光催化還原反應之產物的影響。 先以水熱法製備ZSM-5(Si/Al=15、30、60、120)，再利用含浸法合成Cu/ZSM-5 (Cu=1wt%、3wt%、5wt%、10wt%)，並以場發射掃描式電子顯微鏡(FE-SEM)、孔洞分析儀(BET)、廣角X-ray繞射儀(XRD)、傅立葉轉換紅外線光譜儀(FT-IR)做觸媒的形貌及特性分析。 以Cu/ZSM-5作為觸媒進行光催化還原二氧化碳的批次反應研究，產物分析係以氣相層析儀/火焰離子偵測器(Gas Chromatography/ Flame Ionization Detector；GC/FID)偵測並定量，主要產物為甲醇和乙醇，並探討不同條件下的觸媒對於反應的影響。實驗結果為，隨著矽鋁比的上升，因其比表面積和孔洞體積的增加，亦會使甲醇產量上升；此外，當添加銅的量上升，甲醇產量也隨之增加，由UV-vis證實添加銅會使吸收波段往可見光波段靠近，提高對可見光的吸收。乙醇則只會在觸媒條件為Si/Al=120或Cu=10wt%條件下才會被偵測到，且其含量並不如甲醇有一定規律可循。 綜合上述條件，當觸媒條件為Si/Al=120、Cu=10wt%的反應效果最好，甲醇含量最多，而通過實驗數據，發現其乙醇含量亦為最多，因此在本研究中有最佳的反應效果。

The study investigated the photocatalytic reduction of CO_2 using self-synthesized Cu/ZSM-5, and the effects of different catalytic conditions on the product of photocatalytic reduction. First, the nanocrystalline ZSM-5 with a variety of Si/Al=15、30、60、120 was synthesized by hydrothermal method, and copper is loaded by impregnation method (Cu=1wt%、3wt%、5wt%、10wt%). The Cu/ZSM-5 is analyzed by FE-SEM、BET、XRD、FTIR spectra to show its structure and characteristic. The product analysis was carried out by Gas Chromatography / Flame Ionization Detector (GC / FID). The main products are methanol and ethanol. With the ratio of silica to aluminum, specific surface area and the volume of the pores increase to make more yield of methanol. In addition, the amount of copper added can also increase production of methanol. It can be confirmed by UV-vis spectra because the copper-added catalyst can make absorbed light band close to visible light band. Ethanol will be detected if the condition of catalyst is Si/Al=120 or Cu=10wt%, and its yield doesn’t have some rules to follow. Under the above conditions, when the catalyst conditions were Si / Al = 120, Cu = 10wt% had the most yield of methanol, and the experimental data showed that the yield of ethanol was the most. When the conditions of Cu/ZSM-5 were Si / Al = 120, Cu = 10 wt%, we can find the best effect of photoreduction of CO2.