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毕业论文网 > 毕业论文 > 材料类 > 材料物理 > 正文

甲醛脱除系统的优化设计与性能评价毕业论文

 2021-05-13 23:39:04  

摘 要

Abstract II

1绪论 1

1.1课题背景与意义 1

1.2国内外研究现状 2

1.3实验内容和目的 3

2实验部分 4

2.1催化剂 4

2.2实验主要药品 4

2.3主要测试仪器 5

2.4催化剂毒化测试 5

2.5催化剂表征测试方法 8

3.结果与讨论 10

3.1催化剂初始性能评价 10

3.2毒化测试结果分析与讨论 11

3.3催化剂表征测试结果 16

3.3.1 BET测试结果 16

3.3.2 FTIR测试结果 17

3.3.3 TG测试结果 19

3.4催化剂失活机理探讨 21

3.4.1 SO2对A和B催化剂催化活性的影响 21

3.4.2 VOC对A和B催化剂催化活性的影响 22

4.小结与展望 23

4.1实验小结 23

4.2不足与展望 23

参考文献 25

致 谢 28

摘 要

催化氧化法是室温条件下最有前景的甲醛去除方法,然而其催化剂在实验条件下展现出的高催化活性可能源于高的甲醛测试浓度和简单的气体测试条件,这是不同于真实的居室环境的。本文将以康宁公司提供的两种催化剂(A和B)为研究对象,评估其在室温 ,低甲醛浓度(1~ppm)条件下的催化活性并且探讨SO2,NH3,CO,丙酮和VOC对其催化活性的影响。

研究结果表明:在室温,低甲醛浓度条件下,A系和B系催化剂的初始甲醛转化率达到了较高水平,其均值分别高达89.31%和88.34%,展现出了极佳的催化活性。同时从毒化测试的结果可以看出,SO2和VOC对A系催化剂的催化活性有显著地影响,在毒化3.0h后其甲醛转化率从初始的90.89%和89.63%分别下降到了38.04%和31.07%。而CO,NH3和丙酮对其催化活性并不会造成实质的影响。对于B系催化剂,其对SO2具备优越的抵抗能力,在毒化4.5h之后,其甲醛转化率由初始的87.06%略微升高到了91.76%。NH3和丙酮对其催化活性的影响是非常微弱的,CO对其催化活性的影响只在长时间毒化之后才会显现出来,在毒化19.5h之后,其转化率从88.3%下降到了73%。在VOC的毒化测试中可以发现,VOC对B系催化剂催化活性的影响是有限的,虽然在毒化1.0h之后,其甲醛转化率出现了明显下降,从初始的89.25%下降到了69.24%,但之后的甲醛转化率稳定在70%左右,尤其在毒化4.5h之后,其甲醛转化率仍高达70%。

本文的特色在于:评估了催化剂在室温,~1ppm甲醛浓度条件下的催化活性,研究了SO2,CO,NH3,丙酮和VOC对其催化活性的影响,借助BET,TG,FTIR等测试手段,对催化剂毒化前后理化特性的变化进行表征,初步探讨了催化剂的毒化失活机理。

关键字:甲醛去除 催化剂毒化 失活机理

Abstract

Catalytic oxidation of HCHO at room temperature is considered as the most promising method. However, high catalytic activity of catalyst can be ascribed to high concentration of HCHO and sample measuring conditions under the condition of the experiment, which are different from real world. In this paper, two kinds of catalyst(A and B)offered by Corning company are used to study their catalytic activities at low concentration of HCHO (~1ppm), and possible effects resulting from SO2, NH3, CO, acetone and VOC.

Results show that initial conversion of HCHO reaches high levels for catalyst (A and B), and average conversions reach 89.31% and 88.34%, respectively. Poison results show SO2 and VOC can remarkably suppress catalytic activity of catalyst (A), later 3.0h, their HCHO conversions decrease from 90.89% and 89.63% to 38.04% and 31.07%, respectively. NH3, acetone and CO do not affect the catalytic activities. As for catalyst (B), existence of SO2 can’t weaken catalytic activity. In contrast, the conversion increases from 87.06% to 91.76% slightly. The poison effect of CO could be observed after a long time, and the conversion decreases from 88.3% to 73% after 19.5h exposure. Although VOC can weaken its catalytic activity, the poison effect for the catalyst (B) is limited. The conversion sharply decreases from 89.25% to 69.24% after 1.0h exposure, but it remains the same level for at least a few hours .Especially, the conversion keeps at 70% for 4.5h exposure.

In this paper, catalytic activities of two kinds of catalyst (A and B) are suited at low concentration of HCHO (~1ppm). Meanwhile, possible effects resulting from SO2, NH3, CO, acetone and VOC are tested. With the help of BET, TG, FTIR tests, the physicochemical characteristics of catalyst are studied and the deactivation mechanisms of catalyst are discussed.

Key words: Formaldehyde removal, Catalyst poisoning, Deactivation mechanism

1绪 论

1.1课题背景与意义

随着人们生活水平和节能环保意识的提高,居室的密闭程度越来越高,同时家具、家电的普及和装饰材料的大量使用,使得室内甲醛的浓度普遍超标。室内甲醛的主要释放源为木质家具和木质地砖,特别是其中使用最为广泛的聚脲醛树脂胶黏剂,聚脲醛树脂是一种由尿素和甲醛缩聚而成的氨基树脂胶粘剂,它会慢慢释放甲醛,高温及高湿下脲醛树脂会加快水解,释放甲醛量增多,夏季甲醛释放量高出平时的20%-30%。室内装修时,家具及能大量释放甲醛的建筑材料纷纷进入室内[1]。这些新房装修中广泛使用的木质粘合剂,在一定程度上成为了室内甲醛浓度超标的直接诱因。据统计,装修1~6个月内,甲醛超标率高达80%;装修3年后,甲醛超标率仍高达50%以上[2],同时人们在室内的平均驻留时间为80%-90%,而长期暴露在甲醛环境下,即使是几个ppm的水平,也会对人体的健康造成不可逆转的伤害[3],特别地,当人体长期暴露在低浓度的甲醛气体中,随着甲醛吸入量的累积,累积在人体内的甲醛会对人体的呼吸系统、中枢神经系统、免疫系统、消化系统、血液系统、肾脏及肝脏等造成损害,严重时可能会引起染色体突变诱发口腔癌,鼻咽癌,白血病等癌症[4]。因此消除室内甲醛,改善室内空气环境质量,受到了世界各国的广泛关注,并且纷纷对室内甲醛浓度的阈值作出了严格的限制,其中美国(EPA)给出的限值为0.1mg/m3,日本《室内空气质量标准》给出的限值为0.12mg/m3,我国也于1996年颁布了《室内空气质量标准》,明确规定居室空气中甲醛的最高允许浓度为0.08mg/m3

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