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1.
《化工学报》2016,(11)
以活性炭(AC)为载体制备了不同钨负载量的W_2C/AC催化剂,将其和松木磨木木质素(MWL)机械混合后进行Py-GC/MS(快速热解-气相色谱/质谱联用)实验,考察了钨负载量、催化剂/MWL比例对产物分布的影响,并通过外标法对主要产物(芳烃类和酚类)的真实产率进行了定量分析。结果表明,W_2C/AC催化剂可有效促进木质素的热解解聚生成单酚类产物,并对酚类产物具有脱羰基、脱甲氧基、脱羟基以及加氢的效果,从而促进稳定的酚类产物(不含羰基、甲氧基和不饱和碳碳双键)和芳烃类产物的生成。在4种W2C/AC催化剂中,10%-W2C/AC的催化效果最佳,在催化剂/MWL比例为5时热解产物总产率达到最大值,此时芳烃类和酚类产物的总产率由无催化剂时的21.2 mg·g~(-1)和151.0 mg·g~(-1)增加至102.1 mg·g~(-1)和191.1 mg·g~(-1)。 相似文献
2.
以全钢型废旧轮胎为原料,通过热解、活化、浸渍、焙烧的流程制备了三种热解炭催化剂,分别为轮胎热解炭(Raw char)、轮胎热解活性炭(AC)和负载Zn的活性炭(Zn/AC)。采用N2吸/脱附、SEM、EDS、XRD等表征方法对催化剂进行了一系列表征和分析,发现CO2/H2O活化可显著提高催化剂BET比表面积,最高可达380 m2·g-1,有效改善催化剂表面结构性质,同时浸渍法使催化剂表面负载大量ZnO活性位。对三种催化剂在纤维素热解焦油重整制氢过程中的催化性能进行了研究,发现Raw char(600℃)具有最佳催化效果,相较于空白组(500℃),热解气中H2体积分数提高了12.4%,达到19.3%,其次为Zn/AC(500℃)组的17.8%,实现了低温下催化纤维素焦油热解制得高产率H2。 相似文献
3.
采用等体积浸渍法制备了不同负载量(1%~7%)的CuO/HZSM-5催化剂,在固定床反应器中研究了不同反应温度、溴甲烷流量以及CuO负载量对溴甲烷芳构化催化性能的影响。采用SEM、XRD、N2吸附脱附、TEM、XPS、TG、DSC、NH3-TPD等技术对反应前后的催化剂进行表征。XRD 结果显示活性组分CuO 在HZSM-5上具有很好的分散性,并且反应后Cu晶型不变。NH3-TPD 结果显示3%的CuO 负载后,催化剂强酸量增加。在CuO 负载量为3%,温度为360℃,反应空速为240 ml·g-1·h-1 条件下得到最高的芳烃收率(22.3%)。XPS 结果显示反应后在催化剂上主要的积炭为石墨碳。催化剂稳定性测试结果表明反应40 h内催化活性没有明显下降。 相似文献
4.
以纳米碳纤维/碳毡(CFF)为载体,分别采用碳热氢气还原法和碳热氨气还原法制备了负载型碳化钨、碳氮化钨整体催化剂,XRD结果表明催化剂的活性相分别为W2C和WCxNy, TEM表征发现其粒子尺寸分别为2~40 nm和2~20 nm。采用1 N肼分解推力器评价了上述催化剂的反应性能,W2C/CFF和WCxNy/CFF表现出了相比于Ir/CFF更好的肼分解综合性能:除了初活性略低以外,启动加速性、稳态燃压以及比活性均高于贵金属Ir催化剂。此外,W2C/CFF和WCxNy/CFF催化剂的稳定性明显优于Ir/CFF,这主要是由于CFF载体在贵金属Ir的作用下发生了更显著的甲烷化反应。 相似文献
5.
选取木屑和花生壳作为原料进行生物质热解,研究有机产物分布,催化剂使用Fe、Zn两种金属元素进行改性。通过X射线衍射(XRD)、扫描电镜(SEM)、傅里叶红外(FT-IR)、比表面积测试(BET)对Fe-Zn改性的ZSM-5进行分析。使用闪速裂解-气质联用仪(PY-GC/MS)对原料进行热解,探究生物质催化热解的产物分布变化。催化剂的使用使得芳烃类产物产率获得较大提升,在木屑热解中,Fe负载的分子筛催化获得了酚类的最高产率,比ZSM-5催化热解产率提升18.30%。金属改性催化剂在花生壳热解中,大幅提升了芳烃类产物产率,其中Zn负载催化剂芳烃类产物产率最高,Zn负载催化热解比直接热解的酚类产率降低了18.92%。Zn负载催化获得了最低的酮类产率,与直接热解相比酮类产率降低19.74%,显示出较强的脱羟基效果。此外Zn负载催化和Fe-Zn双金属负载催化在花生壳热解中都大幅降低了酸类产物产率,与直接热解相比酸类产率分别降低了30.46%、36.71%。 相似文献
6.
氟是人类生命活动必需的微量元素之一,但人体摄入过多的氟元素会引发氟斑牙、骨骼变形等氟中毒现象。本文以活性炭 (AC) 为载体,在多孔Al2O3纳米分散液中采用简单超声处理,得到Al2O3/AC复合材料。场发射扫描电镜证明Al2O3成功负载在AC表面,5% Al2O3在AC表面分布均匀。N2吸-脱附测试结果表明Al2O3/AC复合材料的比表面积比AC有明显增加。循环伏安、恒流充放电及电化学阻抗测试结果表明Al2O3的掺杂可以改善AC的离子导电性,提高比电容;5% Al2O3/AC导电性最佳,比电容最高,在7 mmol·L-1 NaF溶液中为92 F·g-1,是AC比电容 (62 F·g-1) 的1.5倍。以Al2O3/AC为正极的电容去离子 (CDI) 脱氟测试,结果表明5% Al2O3/AC电极脱氟量最大,达234 μmol·g-1,远高于纯AC的脱氟量 (115 μmol·g-1)。此外,5% Al2O3/AC电极对F-的选择性吸附性能良好,在含F-、Cl-和SO42-的模拟高氟地下水中采用5% Al2O3/AC电极对应的三组CDI池串联,可脱除80%的F-、25%的Cl-和56%的SO42-,同时经过十次F-吸脱附循环后,氟去除率仍可保持81%,证明5% Al2O3/AC电极对F-具有良好的选择吸附性和循环稳定性。该电极材料制备简单,脱氟选择性好,在CDI过程中有望用于高氟地区地下水的净化脱氟。 相似文献
7.
研究以NaY分子筛粉与Al2O3混合成型后离子交换,引入AlF3和少量稀土(La、Ce)增加催化剂的酸性以提高脱烯烃性能,制备出简单高效的非临氢芳烃脱烯烃催化剂。采用NH3-TPD、XRF、Py-IR和XRD对催化剂进行表征,结果表明,引入AlF3后,催化剂的总酸量增加和L酸酸量增加,B酸酸量减少;引入适量La和Ce组分后,催化剂上中强酸量和B酸酸量增加。以La和Ce改性的催化剂对溴指数540.0 mg·(100g油)-1的原料脱烯烃,产品分布基本无变化,溴指数约稳定在9.0 mg·(100g油)-1。改性催化剂总酸量多、合适中强酸量以及适当提高B酸酸量有利于催化剂脱烯烃性能。 相似文献
8.
采用Ni-P复合改性HZSM-5催化剂催化木质素降解制备高附加值的单酚类化学品,探讨了催化剂种类、金属负载量、反应温度、反应时间以及溶剂种类对木质素催化降解制备酚类化合物的影响。同时采用X射线衍射仪(XRD)、比表面积和孔径分析仪(BET)、化学吸附仪(NH3-TPD)、热重分析仪(TG)以及气相色谱质谱联用仪(GC/MS)对催化剂以及液相产物进行分析表征,同时探讨其催化失活以及再生机制。结果表明:Ni、P高度分散在HZSM-5催化剂的表面,Ni的添加有效地弱化了C-C键,致使β-O-4和α-O-4发生断裂,有效地提高了木质素加氢解聚的活性,减少了焦炭的生成,但催化剂的再生水热稳定性较差,重复使用性较低。当采用甲醇为供氢试剂,在反应温度为220℃,氢气压力为2MPa,反应时间为8h,催化剂负载量为10%,NaOH为共催化剂时,其木质素的转化率为98.6%,酚类化合物的含量达到74.97%。产物以苯酚、愈创木酚和紫丁香酚为主,低温促进了紫丁香酚的产生。 相似文献
9.
为改善活性炭(AC)负载Mo2C基催化剂还原NO2制NO的反应性能,考察硝酸、氨水和双氧水处理后的活性炭对Mo2C/AC结构及反应性能的影响。采用N2物理吸附-脱附、扫描电子显微镜、X射线衍射等对催化剂进行表征。结果表明:催化剂含氧官能团丰富,Mo2C均匀分散,比表面积和孔容比AC0(未预处理AC)小。Mo2C/AC2比表面积和微孔孔容最大,含氧官能团少,有利于Mo2C分散、NO2吸附和还原。3种催化剂在100~400℃转化率随着温度的升高先上升后下降,在250℃时转化率大小关系为:Mo2C/AC2 (80.8%)>Mo2C/AC3 (75.9%)>Mo2C/AC1 (55.2%)。 相似文献
10.
以一种全新的物质--阻燃的FR-1型酚醛树脂电路板基板的真空热解炭渣为原料,采用CO2和KOH活化法制备高性能的活性炭。分别研究了CO2活化法中的活化温度和KOH活化法中的碱炭比对活性炭产品性能的影响。用氮气吸附表征了活性炭的孔结构性质,并检测了产品的亚甲基蓝值和碘值。结果表明,KOH活化所得活性炭有更高的亚甲基蓝值(928.3 mg·g-1 vs 231.5 mg·g-1)、碘值(2442.2 mg·g-1 vs 946.6 mg·g-1)、比表面积(2289 m2·g-1 vs 1198 m2·g-1)和孔体积(1.317 cm3·g-1 vs 0.703 cm3·g-1)。所得产品均达到国家一级品标准。用这种原料制备高性能活性炭不仅解决了废弃物资源化的问题,还开发出一种新的、廉价的制备高性能活性炭的原料和方法工艺。 相似文献
11.
Comparison between tungsten carbide and molybdenum carbide for the hydrodenitrogenation of carbazole
Agnieszka Szymaska-Kolasa Marek Lewandowski Cline Sayag Dominique Brodzki Grald Djga-Mariadassou 《Catalysis Today》2007,119(1-4):35-38
The activity of molybdenum and tungsten carbides in hydrodenitrogenation (HDN) of carbazole was studied. Transition metal carbides (Mo2C and W2C) were synthesized using the temperature-programmed reaction of the appropriate oxide precursor (MoO3 and WO3) with the following gas mixture: 10 vol.% CH4/H2. The structure of the catalysts was characterized using X-ray diffraction, CO chemisorption, high resolution transmission electron microscopy (HRTEM) and BET surface area measurements. From the HRTEM analysis, it could be concluded that the tungsten carbide was thioresistant in our operating conditions (50 ppm of S, pressure = 6 MPa, 553 < T < 653 K, H2/feed volumic ratio = 600). In the case of Mo2C, molybdenum sulphide was observed as single slabs. The activity of catalysts was determined during the hydrodenitrogenation of carbazole at the wide range of temperature (553–653 K) and under a 6 MPa total pressure of H2. The comparison of tungsten carbide and molybdenum carbide has shown higher activity of Mo2C than W2C at the same condition. However, W2C leads to higher amount of isomers of main products, and have higher hydrogenation activity. 相似文献
12.
Minglin Xiang Debao Li Haicheng Xiao Jianli Zhang Wenhuai Li Bing Zhong Yuhan Sun 《Catalysis Today》2008,131(1-4):489-495
Nickel and potassium promoted β-Mo2C catalysts were prepared for CO hydrogenation to higher alcohols synthesis. The results revealed that β-Mo2C produced mainly hydrocarbons, but the addition of potassium resulted in a remarkable selectivity shift from hydrocarbons to alcohols over β-Mo2C. Moreover, it was found that potassium enhanced the ability of chain propagation of β-Mo2C catalyst and led to a higher selectivity to C2+OH. The addition of nickel further enhanced higher alcohols synthesis, which showed the optimum at 1/8–1/6 of Ni/Mo molar ratios. The characterization suggested that there might be a synergistic effect of potassium and nickel on β-Mo2C, which favored the alcohols synthesis. The production of alcohols appeared to be relevant to the presence of Mo4+ species, whereas the formation of hydrocarbons was closely associated with Mo2+ and/or Mo0 species on the surface of β-Mo2C-based catalysts. 相似文献
13.
Comparison of molybdenum carbide and tungsten carbide for the hydrodesulfurization of dibenzothiophene 总被引:5,自引:0,他引:5
The molybdenum and tungsten carbides (Mo2C and W2C) were synthesized, characterized and tested in hydrodesulfurization (HDS) of dibenzothiophene (DBT). The phase purity of these catalysts was established by X-ray diffraction (XRD), and the surface properties were determined by N2 BET specific surface area (Sg) measurements, CO chemisorption and high-resolution transmission electron microscopy (HRTEM). The activities of catalysts were determined during the HDS of DBT at a temperature of 613 K and under a 6 MPa total pressure. Both molybdenum and tungsten carbides were active in HDS of DBT. The reactivity studies showed that molybdenum carbide was more active than tungsten carbide related to weight. However, W2C was shown to possess stronger hydrogenating properties. 相似文献
14.
采用乙醇/(NH4)2SO4两相盐析体系,从酿酒副产物葡萄籽中提取多酚、类黄酮和原花青素。实验结果表明,在室温下用组成(质量分数)为30%乙醇/18%(NH4)2SO4的体系提取葡萄籽中多酚、类黄酮以及原花青素,得率分别为64.54、42.45、23.16 mg·g-1;它们富集于上相乙醇相,萃取回收率分别为97.31%、98.19%、97.92%。室温条件下用2,2-二苯基-1-苦基肼(DPPH)法与2,2'-连氮基-双-(3-乙基苯并二氢噻唑啉-6-磺酸)(ABTS)法测定两相盐析萃取物抗氧化、清除自由基能力,IC50分别为61.85、71.76 mg·L-1,比传统的热回流提取物具有更强的抗氧化活性。 相似文献
15.
A carbon-based sulfonated catalyst was prepared by direct sulfonation and carbonization (in moderate conditions:200 &#176;C, 12 h) of red liquor solids, a by-product of paper-making process. The prepared sulfonated cata-lyst (SC) had aromatic structure, composed of carbon enriched inner core, and oxygen-containing (SO3H, COOH, OH) groups enriched surface. The SO3H, COOH, OH groups amounted to 0.74 mmol·g^-1, 0.78 mmol·g^-1, 2.18 mmol·g^-1, respectively. The fresh SC showed much higher catalytic activity than that of the traditional solid acid catalysts (strong^-acid 732 cation exchange resin, hydrogen type zeolite socony mobile-five (HZSM-5), sulfated zir-conia) in esterification of oleic acid. SC was deactivated during the reactions, through the mechanisms of leaching of sulfonated species and formation of sulfonate esters. Two regeneration methods were developed, and the catalytic activity can be mostly regenerated by regeneration Method 1 and be fully regenerated by regeneration Method 2, respectively. 相似文献
16.
L-threonine (L-Thr) obtained by fermentation often contains vestigial hydrosoluble Pb(Ⅱ), Fe(Ⅱ), L-glutamic acid (L-Glu) etc., which affect the product quality. Poly melamine and L-aspartic acid (L-Asp) resin functional coconut shell activated carbon composite (PMA/AC) was prepared by a pressure relief-dipping-microwave assisted polymerization method for the simultaneous removals. The adsorption capacities of Pb(Ⅱ), Fe(Ⅱ) and L-Glu could reach to 82.34 mg·g-1, 57.82 mg·g-1 and 102.58 mg·g-1 at conditions of pH 5.0, 45℃ and 4 h with an initial concentration of 0.01 mol·L-1, respectively. The present PMA/AC was successfully used to the simultaneous removals of vestigial Pb(Ⅱ), Fe(Ⅱ) and L-Glu from the fermented crude product solution of L-Thr. Moreover, the PMA/AC was carefully characterized by FE-SEM, IR et al. analysis techniques, the results show that abundant PMA particles evenly distributed at the inner and outside surface of AC with a size of (50±20) nm. 相似文献
17.
Adsorption process is acknowledged as an effective option for phenolic wastewater treatment. In this work, the activated carbon(AC) samples after thermal modification were prepared by using muffle furnace. The phenol adsorption kinetics and equilibrium measurements were carried out under static conditions at temperature ranging from 25 to 55 °C. The test results show that the thermal modification can enhance phenol adsorption on AC samples. The porous structure and surface chemistry analyses indicate that the decay in pore morphology and decrease of total oxygen-containing functional groups are found for the thermal modified AC samples. Thus, it can be further inferred that the decrease of total oxygen-containing functional groups on the modified AC samples is the main reason for the enhanced phenol adsorption capacity. For both the raw sample and the optimum modified AC sample at 900 °C, the pseudo-second order kinetics and Langmuir models are found to fit the experimental data very well. The maximum phenol adsorption capacity of the optimum modified AC sample can reach144.93 mg·g-1which is higher than that of the raw sample, i.e. 119.53 mg·g-1. Adsorption thermodynamics analysis confirms that the phenol adsorption on the optimum modified AC sample is an exothermic process and mainly via physical adsorption. 相似文献