本文關(guān)鍵詞：可控的核殼結(jié)構(gòu)鎳基催化劑水熱制備原理及其應(yīng)用　出處：《華東師范大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 負(fù)載型催化劑 水熱合成 制備機(jī)理 生物質(zhì)轉(zhuǎn)化 介孔材料

【摘要】：鎳基催化劑因其低成本和高活性等優(yōu)勢被廣泛應(yīng)用于多種催化工業(yè)過程。我們設(shè)計(jì)將氫型的單晶HBEA分子篩投入到NH4Cl/NH3·H20緩沖溶液,通過一種可調(diào)控的水熱合成方法得到殼層結(jié)構(gòu)的Ni/HBEA。該種催化劑保持了 HBEA分子篩的晶體形貌,大量的高分散鎳納米顆粒主體分布于分子篩表面,少量納米顆粒封裝于分子篩介孔內(nèi)部(擔(dān)載量41 wt%,顆粒尺寸5.9 ±0.7 nm)。我們通過X射線衍射(XRD),掃描電子顯微鏡(SEM),高倍透射電子顯微鏡(TEM),氮?dú)馕?電感耦合等離子體原子發(fā)射光譜(ICP-AES),傅里葉紅外光譜(IR),吡啶為探針分子的紅外光譜(IR-Py),程序升溫還原(TPR)及固體核磁(solid NMR)等表征手段不僅確定了 Ni/HBEA的殼層結(jié)構(gòu),并探究認(rèn)為水熱合成經(jīng)歷了溶硅-硅酸鎳的兩步反應(yīng)過程。其中溶硅過程為決速步,當(dāng)溶解的硅含量大于一定值時(shí),層狀結(jié)構(gòu)的硅酸鎳快速生成。當(dāng)使用NH_4Cl為單一沉淀劑時(shí),溶液環(huán)境無法達(dá)到溶硅要求。而當(dāng)使用NH_3·H_2O為單一沉淀劑時(shí),NH_3·H_2O不僅破壞了分子篩的結(jié)構(gòu)形貌,并且加速了決速步的進(jìn)行,使得中間物質(zhì)由動(dòng)力學(xué)控制的1:1型硅酸鎳(Ni_3Si_2O_5(OH)_4)轉(zhuǎn)化為熱力學(xué)有利的2:1型硅酸鎳(Ni_3Si_4O_(10)(OH)_2)。所得的催化劑在硬脂酸加氫脫氧反應(yīng)中表現(xiàn)出極高的反應(yīng)活性,速率達(dá)到54g·g-1·h-1。另外,我們提出了一種利用水作為溶劑的新型綠色的簡易水熱方法制備各分子篩(HBEA,HUSY,HZSM-5,HMOR)的過渡金屬催化劑。該種方法中,我們將弱酸弱堿鹽,分子篩直接加入水中,無需任何沉淀劑,穩(wěn)定劑,表面活性劑等的添加。因此在制備結(jié)束后,所得催化劑不需要水洗,且濾液相對純凈可以循環(huán)使用,為解決廢水排放的問題提出了新的思路。且催化劑的鎳擔(dān)載量可以通過反應(yīng)時(shí)間控制,鎳納米顆粒的分布因硅酸鎳中間產(chǎn)物的形成而被控制。根據(jù)這一溶硅-形成硅酸鎳的兩步過程,具有弱堿性的鎳鹽以及合適骨架密度的載體組合最優(yōu)。和傳統(tǒng)的制備方法如沉積沉淀法,浸漬法相比,所得到的高鎳擔(dān)載量的催化劑在加氫脫氧反應(yīng),氫化反應(yīng)中具有更高的反應(yīng)活性及選擇性。
[Abstract]:Nickel based catalysts have been widely used in many industrial processes due to their advantages of low cost and high activity. Hydrogen type single crystal HBEA molecular sieve was designed to be used in NH4Cl/NH3 路H20 buffer solution. Ni- / HBEA with shell structure was obtained by a controllable hydrothermal synthesis method. The crystal morphology of HBEA molecular sieve was maintained by the catalyst. A large number of highly dispersed nickel nanoparticles are mainly distributed on the surface of molecular sieve, and a small number of nanoparticles are encapsulated in the mesoporous structure of molecular sieve (the loading capacity is 41 wt%). The particle size is 5.9 鹵0.7 nm 路m ~ (-1). X ray diffraction (XRD), scanning electron microscopy (SEM), high power transmission electron microscopy (TEM) and nitrogen adsorption are used. Inductively coupled plasma atomic emission spectroscopy (ICP-AESN), Fourier transform infrared spectroscopy (FTIR), and pyridine as probe molecule (IR-Pyr). Temperature programmed reduction (Ni/HBEA) and solid NMR (solid NMR) not only confirmed the shell structure of Ni/HBEA. It is concluded that hydrothermal synthesis has undergone two steps of dissolution of silicon and nickel silicate, in which the dissolution of silicon is a rapid step, when the content of dissolved silicon is greater than a certain value. When NH_4Cl was used as a single precipitant, the solution environment could not meet the requirements of dissolved silicon, but when NH_3 路H _ 2O was used as a single precipitating agent. NH_3 路H _ 2O not only destroyed the structure and morphology of molecular sieve, but also accelerated the speed step. Conversion of intermediate matter from 1: 1 type nickel silicate to Nis _ 3Si _ 2O _ 5O _ H _ 4) to thermodynamically advantageous Ni3Si _ 4O _ s _ _ _. The obtained catalyst exhibited very high activity in the hydrodeoxidation of stearic acid. The rate reached 54g 路g -1 路h-1.In addition, a new green hydrothermal method using water as solvent was proposed for the preparation of HZSM-5 with different molecular sieves HBEAA HUSYY and HZSM-5. HMOR) transition metal catalyst. In this method, we add weak acid and weak base salt and molecular sieve directly into water without any addition of precipitators, stabilizers, surfactants, etc. The obtained catalyst does not need washing and the filtrate is relatively pure and can be recycled. A new idea is put forward to solve the problem of wastewater discharge, and the nickel load of the catalyst can be controlled by reaction time. The distribution of nickel nanoparticles is controlled by the formation of nickel silicate intermediate products. Compared with the traditional preparation methods such as deposition method and impregnation method, the catalyst with high nickel loading was obtained in the hydrogenation deoxidation reaction. The hydrogenation reaction has higher activity and selectivity.
【學(xué)位授予單位】：華東師范大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：O643.36

【參考文獻(xiàn)】

相關(guān)期刊論文 前6條

1 陳燕舞;袁騰;王鋒;胡劍青;涂偉萍;;水熱法制備納米VO_2及其相變機(jī)理的研究進(jìn)展[J];材料導(dǎo)報(bào);2016年09期

2 馬冰;張晶晶;崔慧梅;何鳴元;趙晨;;油脂催化轉(zhuǎn)化為綠色燃料的技術(shù)進(jìn)展[J];中國科學(xué):化學(xué);2015年04期

3 譚亞南;韓偉;何霖;王莉;;ZSM-5分子篩合成及其改性研究進(jìn)展[J];四川化工;2011年03期

4 冉獻(xiàn)強(qiáng);;水熱法研究進(jìn)展[J];硅谷;2010年04期

5 李竟先,吳基球,鄢程;納米顆粒的水熱法制備[J];中國陶瓷;2002年05期

6 仲維卓,華素坤;納米材料及其水熱法制備(上)[J];上�；�;1998年11期

，

本文編號：1420937