用于乙炔氢氯化反应的活性炭负载铋无汞催化剂(英文)

采用浸渍法制备了活性炭负载铋无汞催化剂,并通过X射线衍射、氮气物理吸附、透射电镜、扫描电镜和X射线电子能谱等方法对催化剂进行了表征。对催化剂进行了催化乙炔氢氯化反应性能的研究,结果表明,催化剂对乙炔氢氯化反应具有良好的催化性能,活性组分主要以BiOCl的形式存在于催化剂表面。反应过程中积碳的产生使得催化剂活性有所降低。     

水蒸汽活化活性炭及其负载乙炔氢氯化铋基催化剂

以水蒸汽活化的两种活性炭为载体,采用等体积浸渍法制备了一系列Bi/AC催化剂,考察了其乙炔氢氯化反应的催化性能。分别通过氮气吸附脱附实验(BET),扫描电子显微镜(SEM),傅里叶变换红外(FTIR),透射电子显微镜(TEM),X射线粉末衍射(XRD),X射线光电子能谱(XPS)和热重分析(TGA)对活性炭和催化剂进行表征。结果表明：（1）水蒸汽活化重整了活性炭的孔径和孔道,尤其是介孔材质活性炭,增加了其比表面积,形成了新的微孔结构。（2）积碳是Bi/AC催化剂失活的主要原因,水蒸汽活化抑制了积碳,并增加了BiOCl的结晶度和分散性,提高了乙炔氢氯化反应的催化性能。     

小麦粉衍生中孔氮掺杂颗粒炭负载金催化剂用于乙炔氢氯化反应（英文）

聚氯乙烯是五大工程塑料之一,在国民经济中占有重要的地位.基于中国富煤少油缺气的能源格局,我国主要采用基于煤化工的电石法氯乙烯生产工艺,但该工艺必须采用氯化汞催化剂,受到国际限汞公约的影响,无汞催化剂的开发迫在眉睫.其中炭负载金催化剂在该反应中活性最高,近几年来取得了较大进展,有望实现产业化.氮掺杂的炭材料在诸多反应中展现了较好的性能,其负载金属催化剂可以有效提高金属的分散度及稳定性,成为近几年多相催化领域的一个研究热点.最近我们课题组报道了一种氮掺杂中孔成型的制备方法:以小麦粉为原料,通过直接炭化法制备了氮掺杂中孔成型炭,这种氮掺杂中孔成型炭作为无汞催化剂在乙炔氢氯化反应中显示出了优异的催化性能.小麦粉衍生的氮掺杂中孔成型炭具有成型容易.原料价廉易得、易于放大生产等优点,是优选的工业化催化剂的载体.本文以这种氮掺杂的成型炭为载体制备了负载型金催化剂,研究其催化乙炔氢氯化性能.结果表明,氮的掺杂使得中孔炭负载金(Au/N-MC)催化剂上乙炔氢氯化活性明显提高.在氯化氢/乙炔比例1.1、反应温度180℃、乙炔空速600 h~(-1)的条件下,Au/N-MC上的乙炔转化率为50%,是Au/MC催化剂活性的2倍.通过对催化剂的表征发现,氮的掺杂能有效地锚定Au/N-MC催化剂中活性组分Au~(3+),抑制催化剂制备过程中Au~(3+)还原为Au~0,从而提高催化剂活性和稳定性.小麦粉衍生的氮掺杂中孔炭的原料廉价易得,生产工艺简单,易成型,也容易实现工业化生产,是负载型金属催化剂的优良载体,其负载的无汞催化剂性能优越,有望取代电石法氯乙烯产业的汞催化剂,成为新一代无汞催化剂.     

SnCl2-ZnCl2/C无汞乙炔氢氯化催化剂的制备与优化

利用超声波制备了SnCl2-ZnCl2/C无汞乙炔氢氯化催化剂,同时加入稀土化合物以稳定催化剂的性能。通过黄金分割法与抛物线法确定了活性组分SnCl2与ZnCl2的最优质量比为2∶1。优选制备工艺,发现在反应温度140℃,乙炔空速300 h-1,V(HCl)/V(C2H2)=1.10时,由0.67 g SnCl2、0.33 g ZnCl2、0.05 g Tb4O7以及4 g焙烧过的活性炭组成的催化剂,其乙炔平均转化率最高,为67.70%。实验表明,载体的处理方式是影响催化剂性能的重要因素。     

乙炔氢氯化反应铜系催化剂的反应机理

以电石乙炔法制备氯乙烯的非汞催化反应体系为研究对象,用量子化学密度泛函理论(DFT)研究了以Cu基催化剂为代表的非汞催化剂的反应机理.模拟了以石墨烯为载体的乙炔氢氯化反应在Cu基催化剂作用下的两条反应路径及其过渡态.将该反应机理应用到不同金属氯化物催化剂中,通过计算相应的活化自由能和反应速率常数讨论了不同金属氯化物的活性顺序,与实验结果相比较印证了反应机理的合理性.讨论了Cu基催化剂的失活原因以及在载体中掺杂氮原子或磷原子对反应活性的影响.为非贵金属无汞催化剂的研究提供了一定的理论指导.     

新型载铜碳纳米管催化剂的制备及其对乙炔氢氯化反应的催化活性

羧基碳纳米管与铜乙二胺溶液反应后于200℃焙烧制得新型载铜碳纳米管催化剂(Cu-CNTs)。考察了Cu-CNTs对乙炔氢氯化反应的催化活性。结果表明,Cu-CNTs相对于活性炭负载铜催化剂具有更好的催化活性,且更不易失活。     

乙烯基乙炔氢氯化反应合成氯丁二烯催化剂的研究

乙炔法氯丁橡胶单体2-氯丁二烯—1,3(简称氯丁二烯或CB)生产目前国内和日本电气化学公司等仍采用传统的Nieu land型催化剂,由乙烯基乙炔(MVA)氢氯化制得。但存在二氯丁烯等副产物生成量大,选择性低,消耗高,污染环境等问题。国内外有一些氯丁二烯合成催化剂改进的专利报道,本文对氯丁二烯合成催化剂也进行了研究,得到有益的结果。     

Cu/HY催化剂在乙炔氢氯化反应中的性能及其失活原因

采用等体积浸渍法制备了以分子筛为载体的铜基无汞催化剂(Cu/HY),在固定床反应器中,考察了Cu/HY催化剂用于乙炔氢氯化反应制取氯乙烯的催化性能,并采用扫描电子显微镜(SEM)、能量散射光谱(EDS)、电感耦合等离子光谱(ICP-AES)、氮气吸脱附(BET)、热重分析(TG)、透射电子显微镜(TEM)、X射线粉末衍射(XRD)和X射线光电子能谱(XPS)表征手段对反应前后的催化剂进行了表征和分析。 结果表明,反应温度为160 ℃,常压,空速为120 h^-1,V(HCl)/V(C₂H₂)=1.25,Cu的负载质量分数为15%时,Cu/HY催化剂的乙炔氢氯化性能最佳,乙炔转化率可达84%,氯乙烯选择性始终大于95%,且具有较好的稳定性;通过表征分析,认为催化剂表面形成积碳,铜活性物种的还原、团聚和流失是导致Cu/HY催化剂活性下降的主要原因。     

Active carbon supported S-promoted Bi catalysts for acetylene hydrochlorination reaction

We synthesized a S doped Bi/AC catalyst for acetylene hydrochlorination. The addition of H₂SO₄ changes the structure of the Bi atoms in the catalyst, resulting in the improvement of the specific surface areas and catalytic efficiency of the Bi-based catalyst under reaction conditions.     

Carbon-supported binary Li-Sn catalyst for acetylene hydrochlorination

The study of a novel catalyst containing LiCl and SnCl₂ (LiSn/AC) for acetylene hydrochlorination has been reported in this paper. Furthermore, the performance of both high activity (98.3%) and selectivity (>98.0%) are achieved by LiSn/AC catalysts under the reaction temperature of 200 °C and C₂H₂ hourly space velocity of 30 h^?1. The structural characteristics of the Sn based catalysts were deeply researched via BET, XRD, TEM, TPR, C₂H₂-TPD, XPS and TG techniques. According to these characteristic results, we proposed that the presence of Sn²⁺ exhibited better activity and stability than that of Sn⁴⁺ in Sn based catalysts. Additionally, LiCl additives not only can restrain the oxidation of Sn²⁺ and the loss of Sn⁴⁺ in fresh Sn based catalysts but also make the Sn^δ+ (δ = 2,4) species dispersed well on the surface of support. Therefore, the adsorption capacity of C₂H₂ and HCl was enhanced in LiSn/AC, which exhibited the better catalytic performance than that of Sn based catalyst.     

The catalytic performance of metal-free defected carbon catalyst towards acetylene hydrochlorination revealed from first-principles calculation

Defected carbon materials as a metal-free catalyst have shown superior stability and catalytic performance in the acetylene hydrochlorination reaction. Through density functional theory (DFT) calculations, for the first time, several different defected configurations comprising mono and divacancies and Stone Wales defect on single-walled carbon nanotubes (SWCNTs) have been used as a direct catalyst for acetylene hydrochlorination reaction. These defective sites on SWCNTs are the most active site for acetylene hydrochlorination reaction compare to pristine SWCNT. The different configurations of defects have different electronic structures, which specify that monovacancy defects have more states adjacent to the Fermi level. The reactant acetylene (C₂H₂) adsorbed strongly compared to hydrogen chloride (HCl) and expected to be the initial step of the reaction. Acetylene adsorbed strongly at monovacancy defected SWCNT compared to other investigated defects. Reaction pathway analysis revealed that mono- and divacancy defected SWCNTs have minimum energy barriers and show extraordinary performance toward acetylene hydrochlorination. This work suggests the potential of metal-free defected carbon in catalyzing acetylene hydrochlorination and provides a solid base for future developments in acetylene hydrochlorination.     

Efficient and stable Ru(III)-choline chloride catalyst system with low Ru content for non-mercury acetylene hydrochlorination

Herein, we report an excellent, supported Ru(III)-ChCl/AC catalyst with lower Ru content, where the ionic complex ChRuCl₄ serves as the active component for acetylene hydrochlorination. The prepared heterogeneous Ru-10%ChCl/AC catalyst shows excellent activity and long-term stability. In this system, ChCl provides an environment for the ChRuCl₄ to be stabilized as Ru(III), thus suppressing the reduction of the active species and the aggregation of ruthenium species during the reaction. The interaction between reactants and catalyst species was investigated by catalyst characterizations in combination with DFT calculations to disclose the effect of the ChRuCl₄ complex and ChCl on the catalytic performance. This inexpensive, efficient, and long-term catalyst is a competitive candidate for application in the hydrochlorination industry.     

Tin-sulfur based catalysts for acetylene hydrochlorination

In the present work, tin-sulfur based catalysts were prepared using Na₂SO₃ and (CH₃SO₃)₂Sn and were tested in acetylene hydrochlorination. Based on the analysis of experiments results, the acetylene conversion of (CH₃SO₃)₂Sn/S@AC is still over 90%after a 50 h reaction, at the reaction conditions of T = 200 ^oC, V_HCl/V_C2H2 = 1.1:1.0 and C₂H₂-GSHV = 15 h^–1. According to the results of X-ray photoelectron spectroscopy (XPS), HCl adsorption experiments, and acetylene temperature programmed desorption (C₂H₂-TPD), it is reasonable to conclude that the interaction between Sn and S not only can retard the oxidation of Sn²⁺ in catalysts but also strengthen the reactant adsorption capacity of tin-based catalysts. Furthermore, results obtained from nitrogen adsorption/desorption and XPS proved that the CH₃SO₃- can effectively decrease the coke deposition of (CH₃SO₃)₂Sn/AC and thus prolong the lifetime of (CH₃SO₃)₂Sn/AC.     

原位掺杂法制备氮掺杂中孔炭及乙炔氢氯化反应性能

聚氯乙烯(PVC)是世界五大工程塑料之一,在工业、农业、建筑、电力及通信等领域有着非常广泛的应用.氯乙烯(VCM)作为合成 PVC的单体,其生产工艺以源于煤化工路线的乙炔氢氯化法工艺为主,但是该工艺目前采用的是氯化汞催化剂,存在较为严重的环境污染问题.开发新型无汞催化剂成为电石法生产 VCM亟待解决的问题.氮掺杂炭基非金属催化剂成本低廉,制备简单,在诸多反应中展现了较好的性能,成为近几年多相催化领域的一个研究热点,在乙炔氢氯化反应中也具有较好的活性,但是对活性中心的鉴别及制备方法的研究还有待深入.本文报道了一种一步原位尿素掺杂氮的中孔炭的制备方法,采用氮气吸附-脱附、高分辨透射电子显微镜、元素分析和X射线光电子能谱(XPS)等表征手段研究了氮掺杂中孔炭的结构、氮含量及存在形式,并与两步尿素改性方法做了对比,探究了氮掺杂形式与中孔炭乙炔氢氯化反应性能之间的关系,同时考察了尿素用量对氮掺杂中孔炭的氮含量和存在形式的影响.元素分析结果表明,原位合成法能有效地将氮掺杂进骨架中,随着制备过程中尿素用量增加,得到的氮掺杂中孔炭中的氮含量增加,可达3.6 wt%.后处理法的掺氮效果较差,材料氮含量仅为0.2 wt%. XPS测试进一步表明,一步法原位法可以得到石墨型氮占据主导地位的氮掺杂中孔炭,石墨型氮约占70%左右,后处理制备的氮掺杂中孔炭中石墨氮、吡啶氮和吡咯氮三种形式含量相差不大.对不同方法合成的氮掺杂介孔炭的乙炔氢氯化反应催化性能进行了评价,结果显示,无论是原位合成还是后处理制备的氮掺杂中孔炭,其活性均比中孔炭得到一定提升.氮的引入能有效提高材料的乙炔氢氯化反应性能.原位合成法制备的氮掺杂中孔炭在乙炔氢氯化反应中的催化性能远高于后处理法.对于原位合成的氮掺杂中孔炭,在一定范围内,随着氮含量的增加,催化活性提高,但当尿素用量过高时,虽然氮含量增加,催化活性却有所下降,这归因于孔结构坍塌和比表面积下降.     

Pyrrolidone ligand improved Cu‐based catalysts with high performance for acetylene hydrochlorination

A series of Cu‐pyrrolidone/spherical activated carbon (SAC) catalysts were prepared via a simple incipient wetness impregnation method and then assessed in acetylene hydrochlorination, and the catalytic evaluation result indicated that the 1‐methyl‐2‐pyrrolidinone (NMP) ligand was found to be the most effective one to significantly improve the activity and stability of Cu catalyst. The catalyst with the optimal molar ratio of NMP/Cu = 0.25 showed 94.2% acetylene conversion at 180°C and an acetylene gas hourly space velocity of 180 h^?1. Moreover, the acetylene conversion of Cu‐0.25NMP/SAC remained stable over 99.1% for about 220 h under the industrial condition. Transmission electron microscopy (TEM) analyses proved that NMP ligand improved the dispersion of Cu species. In addition, hydrogen temperature‐programmed reduction (H₂‐TPR), X‐ray photoelectron spectra (XPS), thermogravimetric analysis (TGA), and Brunner–Emmet–Teller (BET) indicated that the additive of NMP was preferential to stabilize the catalytic active Cu⁺ and Cu²⁺ species and inhibit the reduction of Cu^α+ to Cu⁰ during the preparation process and reaction, hence restraining the coke deposition. Furthermore, the steady coordination structure between Cu and NMP was confirmed by Fourier‐transform infrared spectra (FT‐IR) and Raman combining with density functional theory (DFT) calculation, which could effectively lower the adsorption energy of catalyst for C₂H₂ and inhibit the serious carbon deposition caused by excessive acetylene self‐accumulation. Our findings suggest that the efficient, well‐stabilized cost‐effective, and environmentally friendly Cu catalyst has great potential in acetylene hydrochlorination.