發(fā)布時間：2018-05-20 16:04

  本文選題：Pd + CeO_2納米管��； 參考：《浙江大學(xué)》2015年碩士論文

【摘要】：CO氧化反應(yīng)在多相催化領(lǐng)域具有重要的研究意義和應(yīng)用前景。CO2激光器、CO氣體防毒面具、封閉體系、質(zhì)子交換膜燃料電池所用到的氫氣等都需要脫除CO。同時,CO氧化反應(yīng)作為研基礎(chǔ)究的模型反應(yīng),可以用來研究催化劑的結(jié)構(gòu)特征、吸附／脫附性能、氧化還原能力以及反應(yīng)機(jī)理等。貴金屬Pd催化劑因其良好的CO低溫氧化性能而受到研究者的廣泛關(guān)注。研究表明,Pd顆粒的結(jié)構(gòu)與分散度、載體的種類和結(jié)構(gòu)以及催化劑的制備方法等因素都會影響其活性。同時,進(jìn)一步提高納米Pd催化劑的穩(wěn)定性,防止金屬顆粒在反應(yīng)中團(tuán)聚也具有重要的研究價值和意義。本文以Pd納米顆粒為活性中心,Ce02納米管為載體,制備得到新穎的具有納米管結(jié)構(gòu)的負(fù)載型Pd納米催化劑和核殼型Pd納米催化劑,以期提高Pd納米催化劑在CO氧化反應(yīng)中的活性和穩(wěn)定性,結(jié)果表明：1.以Ce02納米管作為載體制備得到的負(fù)載型Pd納米催化劑在CO氧化中表現(xiàn)出優(yōu)良的低溫活性。在CO與02體積比為1：4,空速為12000 mL·gcat-1·H-2的反應(yīng)條件下,該催化劑能在100℃實(shí)現(xiàn)CO的完全轉(zhuǎn)化。與以普通Ce02作為載體的負(fù)載型Pd納米催化劑相比,該催化劑具有的獨(dú)特納米管結(jié)構(gòu)對反應(yīng)活性更有利。2.以Si02為殼層,包覆負(fù)載Pd納米顆粒的Ce02納米管,形成核殼型Pd納米催化劑。該催化劑在CO氧化反應(yīng)中表現(xiàn)出良好的低溫活性,在上述相同的反應(yīng)條件下,能在140℃實(shí)現(xiàn)CO的完全轉(zhuǎn)化。與未包覆Si02殼層的負(fù)載型Pd納米催化劑相比,其活性雖有所下降,但該催化劑表現(xiàn)出更優(yōu)良的高溫穩(wěn)定性。經(jīng)過700℃高溫老化的穩(wěn)定性實(shí)驗(yàn)后,該催化劑保持結(jié)構(gòu)穩(wěn)定,Pd納米顆粒未明顯長大,反應(yīng)活性保持穩(wěn)定；而負(fù)載型Pd納米催化劑經(jīng)過相同穩(wěn)定性實(shí)驗(yàn)后,出現(xiàn)明顯的Pd納米顆粒長大和團(tuán)聚現(xiàn)象,其活性顯著下降。
[Abstract]:Co oxidation is of great significance in the field of heterogeneous catalysis. Co gas mask, sealing system and hydrogen used in proton exchange membrane fuel cells need to be removed from CO 2 laser. As a model reaction, CO oxidation reaction can be used to study the structure characteristics, adsorption / desorption performance, redox ability and reaction mechanism of the catalyst. Noble metal PD catalysts have attracted much attention due to their excellent low temperature oxidation of CO. The results show that the structure and dispersion of Pd particles, the type and structure of support, and the preparation method of catalyst will affect their activity. At the same time, it is of great value and significance to improve the stability of nanometer PD catalyst and prevent metal particles from agglomeration in the reaction. In this paper, supported PD nanocatalysts with nanotube structure and core-shell PD nanocatalysts were prepared by using PD nanoparticles as active center and Ce02 nanotubes as support. In order to improve the activity and stability of PD nanometer catalyst in CO oxidation reaction, the results showed that 1: 1. The supported PD nanocatalysts prepared on Ce02 nanotubes showed excellent low temperature activity in CO oxidation. When the volume ratio of CO to O2 is 1: 4 and the space velocity is 12000 mL gcat-1 H-2, the catalyst can realize the complete conversion of CO at 100 鈩，

本文編號：1915327