光催化降解低濃度甲醛工藝研究與反應(yīng)器設(shè)計(jì)
發(fā)布時(shí)間：2018-08-24 20:35
【摘要】：目前室內(nèi)環(huán)境污染問題嚴(yán)重,而光催化技術(shù)無疑提供一個(gè)新穎的研究思路,我們可以利用光催化技術(shù)降解室內(nèi)的空氣污染物,并且越來越多的人對(duì)光催化技術(shù)感興趣并投身于此。光催化反應(yīng)器是光催化技術(shù)應(yīng)用的載體,其內(nèi)部的動(dòng)力學(xué)過程復(fù)雜且影響因素繁多。反應(yīng)器性能優(yōu)化已成為光催化技術(shù)成功應(yīng)用的一個(gè)關(guān)鍵步驟。本文以甲醛為目標(biāo)污染物,在自行設(shè)計(jì)加工的光催化裝置內(nèi)進(jìn)行反應(yīng),研究了光催化反應(yīng)動(dòng)力學(xué)的過程,并具體討論了反應(yīng)器的設(shè)計(jì)及優(yōu)化,考察了甲醛降解過程的影響因素。本文的主要結(jié)論如下:(1)以光催化降解動(dòng)力學(xué)為基礎(chǔ)依據(jù),分析現(xiàn)有催化劑膜厚模型,尋找以金屬鎳網(wǎng)為載體的理論膜厚模型,確定最佳膜厚,通過實(shí)驗(yàn)發(fā)現(xiàn)現(xiàn)有模型可以很好的預(yù)測(cè)以泡沫鎳網(wǎng)為載體的光催化膜厚。通過實(shí)驗(yàn)和預(yù)測(cè)均發(fā)現(xiàn),當(dāng)催化劑膜厚增加時(shí),降解率先增加后穩(wěn)定。實(shí)驗(yàn)得到最優(yōu)催化劑膜厚為86 nm與預(yù)測(cè)值基本吻合,通過在同一條件下對(duì)比其他催化劑如Ti02, Cu2O, BiVO4, g-C3N4可知,當(dāng)催化劑膜厚增加時(shí),甲醛降解率先增加后穩(wěn)定在某一數(shù)值。實(shí)驗(yàn)得到最優(yōu)催化劑膜厚均為86nm。說明此模型適用于其他不同種類的催化劑。(2)對(duì)比研究不同催化劑Ti02, BiVO4,Cu2O的結(jié)構(gòu)(晶粒尺寸、BET、禁帶寬度)和降解低濃度污染物來評(píng)價(jià)其性能優(yōu)劣,優(yōu)選出光催化性能較優(yōu)的材料。通過結(jié)構(gòu)分析和降解實(shí)驗(yàn)發(fā)現(xiàn),當(dāng)甲醛初始濃度較低時(shí),BiV04降解率優(yōu)于其他,隨濃度增加,催化劑降解率均呈上升趨勢(shì),TiO2-1 (T-1).、Ti02-2 (T-2)降解率增加顯著。隨環(huán)境濕度增大,降解率先上升后下降,BiV04-1 (B-1)、BiV04-2 (B-2)降解率下降的較為緩慢。同一物質(zhì)當(dāng)晶粒尺寸越小BET越大,其降解率越好。T-2比B-1有更好的穩(wěn)定性。為下一步反應(yīng)器的設(shè)計(jì)提供更加高效穩(wěn)定的光催化劑。(3)依據(jù)高效和節(jié)能的原則,以甲醛,光子和催化劑協(xié)調(diào)為目的,設(shè)計(jì)了四種光催化反應(yīng)器,并對(duì)其光催化降解社能進(jìn)行了實(shí)驗(yàn)研究。一字型反應(yīng)器的斯坦頓數(shù)(Stm)和吸附平衡常數(shù)(K)較大,說明對(duì)流傳質(zhì)能力較強(qiáng),但其反應(yīng)有效度η和反應(yīng)速率常數(shù)k明顯很小,表明其反應(yīng)能力很差,傳質(zhì)-反應(yīng)能力并不匹配。當(dāng)η接近0或者1均不好,只有在0.5時(shí),說明反應(yīng)速率和傳質(zhì)速率相當(dāng),催化劑的傳質(zhì)-反應(yīng)能力匹配。所以效果最好的是45°型反應(yīng)器。
[Abstract]:At present, the problem of indoor environmental pollution is serious, and photocatalytic technology undoubtedly provides a novel research idea. We can use photocatalytic technology to degrade indoor air pollutants. And more people are interested in and devoted to photocatalytic technology. Photocatalytic reactor is the carrier of photocatalytic technology. The optimization of reactor performance has become a key step in the successful application of photocatalytic technology. In this paper, the kinetics of photocatalytic reaction was studied in a photocatalytic device designed and processed with formaldehyde as the target pollutant. The design and optimization of the reactor were discussed in detail, and the factors influencing the degradation of formaldehyde were investigated. The main conclusions are as follows: (1) on the basis of photocatalytic degradation kinetics, the existing film thickness model of catalyst is analyzed, and the theoretical film thickness model based on metal nickel mesh is found to determine the best film thickness. It is found that the existing models can predict the thickness of photocatalytic film with nickel foam mesh as the carrier. It was found by experiments and predictions that when the film thickness of the catalyst increased, the degradation increased first and then stabilized. The experimental results show that the optimal film thickness of the catalyst is 86 nm, which is consistent with the predicted value. Compared with other catalysts such as Ti02, Cu2O, BiVO4, g-C3N4 under the same conditions, the degradation of formaldehyde is firstly increased and then stabilized at a certain value when the film thickness of the catalyst increases. The results show that the optimal film thickness of the catalyst is 86 nm. This model is suitable for other kinds of catalysts. (2) the structure (grain size and band gap) of Ti02, BiVO4,Cu2O and the degradation of low concentration pollutants are compared to evaluate its performance and select the materials with better photocatalytic performance. The results of structure analysis and degradation experiments showed that the degradation rate of BiV04 was better than that of others when the initial concentration of formaldehyde was low, and the degradation rate of TiO2-1 (T-1). Ti02-2 (T-2) increased significantly with the increase of formaldehyde concentration. With the increase of environmental humidity, the degradation rate of BiV04-1 (B-1) and BiV04-2 (B-2) decreased slowly. The smaller the grain size of the same material, the larger the BET, the better the degradation rate. T-2 has better stability than B-1. (3) according to the principle of high efficiency and energy saving, four kinds of photocatalytic reactors are designed for the purpose of coordination of formaldehyde, photon and catalyst. The photocatalytic degradation mechanism was studied experimentally. The Stanton number (Stm) and adsorption equilibrium constant (K) of the single-type reactor are larger, which indicates that the convection mass transfer ability is strong, but the reaction efficiency 畏 and the reaction rate constant k are obviously small, which indicates that the reaction ability is very poor and the mass transfer and reaction ability is not matched. When 畏 is close to 0 or 1, only when 畏 is close to 0 or 1, the reaction rate is equal to the mass transfer rate, and the mass transfer ability of the catalyst is matched. So the best effect is the 45 擄reactor.
【學(xué)位授予單位】：天津科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：X51
本文編號(hào)：2201964
[Abstract]:At present, the problem of indoor environmental pollution is serious, and photocatalytic technology undoubtedly provides a novel research idea. We can use photocatalytic technology to degrade indoor air pollutants. And more people are interested in and devoted to photocatalytic technology. Photocatalytic reactor is the carrier of photocatalytic technology. The optimization of reactor performance has become a key step in the successful application of photocatalytic technology. In this paper, the kinetics of photocatalytic reaction was studied in a photocatalytic device designed and processed with formaldehyde as the target pollutant. The design and optimization of the reactor were discussed in detail, and the factors influencing the degradation of formaldehyde were investigated. The main conclusions are as follows: (1) on the basis of photocatalytic degradation kinetics, the existing film thickness model of catalyst is analyzed, and the theoretical film thickness model based on metal nickel mesh is found to determine the best film thickness. It is found that the existing models can predict the thickness of photocatalytic film with nickel foam mesh as the carrier. It was found by experiments and predictions that when the film thickness of the catalyst increased, the degradation increased first and then stabilized. The experimental results show that the optimal film thickness of the catalyst is 86 nm, which is consistent with the predicted value. Compared with other catalysts such as Ti02, Cu2O, BiVO4, g-C3N4 under the same conditions, the degradation of formaldehyde is firstly increased and then stabilized at a certain value when the film thickness of the catalyst increases. The results show that the optimal film thickness of the catalyst is 86 nm. This model is suitable for other kinds of catalysts. (2) the structure (grain size and band gap) of Ti02, BiVO4,Cu2O and the degradation of low concentration pollutants are compared to evaluate its performance and select the materials with better photocatalytic performance. The results of structure analysis and degradation experiments showed that the degradation rate of BiV04 was better than that of others when the initial concentration of formaldehyde was low, and the degradation rate of TiO2-1 (T-1). Ti02-2 (T-2) increased significantly with the increase of formaldehyde concentration. With the increase of environmental humidity, the degradation rate of BiV04-1 (B-1) and BiV04-2 (B-2) decreased slowly. The smaller the grain size of the same material, the larger the BET, the better the degradation rate. T-2 has better stability than B-1. (3) according to the principle of high efficiency and energy saving, four kinds of photocatalytic reactors are designed for the purpose of coordination of formaldehyde, photon and catalyst. The photocatalytic degradation mechanism was studied experimentally. The Stanton number (Stm) and adsorption equilibrium constant (K) of the single-type reactor are larger, which indicates that the convection mass transfer ability is strong, but the reaction efficiency 畏 and the reaction rate constant k are obviously small, which indicates that the reaction ability is very poor and the mass transfer and reaction ability is not matched. When 畏 is close to 0 or 1, only when 畏 is close to 0 or 1, the reaction rate is equal to the mass transfer rate, and the mass transfer ability of the catalyst is matched. So the best effect is the 45 擄reactor.
【學(xué)位授予單位】：天津科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：X51
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