煤催化加氢气化研究进展

煤加氢气化制天然气技术具有工艺路径短、热效率高等优点,其应用基础研究备受关注。但煤中存在部分致密的芳香碳结构,加氢反应性较差,即使在苛刻的反应条件下(~1 000℃、~7 MPa H_2),仍难以转化。通过引入催化剂,进行煤催化加氢气化可在温和的反应条件下实现煤的碳转化率和CH_4收率的同步提高。论述了碱金属(K、Na等)、碱土金属(Ca)和过渡金属(Fe、Co、Ni等)催化剂对模型碳加氢气化的催化作用原理。探讨了反应温度、氢气压力、和碳结构对C-H_2催化反应的影响规律,分析了适用于原煤催化加氢气化的最佳催化剂及工艺条件,并从CH_4和轻质液体焦油等产物生成规律、煤中碳结构随着反应进行的衍变过程等角度,讨论了催化剂分别对煤加氢热解和热解半焦加氢气化的催化作用行为。提出了煤催化加氢气化联产CH_4和轻质液体焦油技术从基础走向应用的进一步研究建议。现有研究结果表明,过渡金属与碱土金属组成的二元催化剂(Fe/Co/Ni-Ca)对煤加氢气化的活性较高。过渡金属元素在反应过程中主要提供C-H_2反应所需的活性氢,并削弱C—C键的键能;碱土金属元素Ca主要促进Fe/Co/Ni的分散,防止其发生硫中毒失活,并增强Fe/Co/Ni与碳之间的相互作用。温度升高一方面为化学键断裂过程提供了更高能量,加速C-H_2反应,另一方面促进催化剂在煤结构中扩散,提升催化剂的供氢和断键效率。升高压力促进了活性氢的供应,同时CH_4浓度得到稀释,反应向生成CH_4的方向移动。以5%Co-1%Ca为催化剂,在850℃、3 MPa H_2反应条件下,30 min内可同时达到90.0%的碳转化率和77.3%的CH_4收率。Co-Ca催化剂在煤加氢热解过程中具有催化解聚和催化加氢的作用,提高焦油和CH_4收率,同时催化剂在煤加氢热解过程中对煤结构产生催化活化作用,使得生成的半焦具有较高的气化活性。煤催化加氢气化的机理研究目前仍处于推测阶段,另外,该技术气化剂、煤种的适应性,催化剂循环利用性能有待进一步阐明。     

载体改性对Cu/B/Al2O3结构及其催化醋酸仲丁酯加氢性能的影响

以γ-Al₂O₃为载体采用分步浸渍法制备了不同金属氧化物进行载体改性的Cu/B/M/Al₂O₃(M=Mg,Ca,Ni)催化剂,并测试了其催化醋酸仲丁酯加氢反应的性能。结果表明,以NiO进行载体改性的催化剂导致酯加氢反应中大量酸催化产物及烃类出现;以MgO进行载体改性不利于金属Cu的分散且催化剂的结构稳定性较差;以CaO对γ-Al₂O₃载体进行改性不仅能够促进金属Cu的分散,提高催化剂的酯加氢活性和产物选择性,而且可以有效减少反应中非活性碳物种在催化剂表面的沉积。     

铁系催化剂催化淖毛湖煤加氢液化反应研究

煤直接液化的关键是催化剂体系的优化。文中采用小型加氢反应装置和多种仪器分析方法,研究了铁系催化剂催化淖毛湖煤直接加氢液化反应性能及过程杂原子分布特征。发现升华S作为助剂较SO_4~(2-)催化效果更好;FeOOH和S对沥青质有较好的催化转化作用。复合Fe/Ni催化活性较单Fe活性略低,对沥青质的转化效果较差。液化产物中正己烷可溶组分含有较多的正构烷烃,碳数可达到C_(28)。含氮杂环化合物中,主要含喹啉和异喹啉。含硫杂环化合物主要为噻吩类,苯并噻吩类和苯硫醚等。硫化物部分来自原煤并与添加的硫助剂有关。液化过程中氧元素和硫元素反应活性较高,氮元素反应活性较低,其在液化残渣中的含量几乎不变。     

铁系催化剂对煤高温快速液化的影响

以兖州煤为研究对象,采用微型反应釜研究了两种铁系催化剂对煤高温快速液化的影响.结果表明,担载Fe2S3的催化剂和高分散铁系催化剂对煤的热解行为影响较小;担载Fe2S3催化剂促进了氢气参与反应和煤液化产物向轻质化转化,在优秀和足量的供氢溶剂条件下,溶剂的供氢速度明显优于氢气转换的供氢速度,催化剂的作用不明显;对比添加高分散铁系催化剂并加助剂S和添加Fe2S3催化剂的煤高温快速液化,发现元素S的作用与S和主催化剂铁的结合形态有关.     

微米级蛋壳型Ni/SFC3R催化C5石油树脂加氢反应

以流态化催化裂化废触媒(SFC3R)为载体,采用浸渍法制备了微米级蛋壳型Ni/SFC3R催化剂,利用FIB(聚焦离子束)-EDX、XRD、H2-TPR和TEM技术对催化剂结构、表面物相和还原性进行了表征;考察了反应温度、压力和时间对C5石油树脂加氢反应的影响,并应用Gardner色号、软化点、GPC、FTIR和1HNMR对加氢改性C5石油树脂进行性能和结构分析。结果表明,SFC3R为分子筛结构,Ni活性组分主要分布在载体外层形成蛋壳分布,Ni O的平均粒径为21.5 nm,具有良好的分散性。C5石油树脂加氢的最优反应条件为:温度280℃,压力8.0 MPa,时间5 h,所得的加氢改性C5石油树脂Gardner色号1,颜色为水白色,硫含量10 mg/kg,溴值为0.45 g Br/100 g,C5石油树脂中的不饱和键加氢基本达到饱和,表明蛋壳型Ni/SFC3R具有优良的C5石油树脂催化加氢性能。     

共浸法制备高分散Ni/CCA催化剂及顺酐加氢性能

为获得高分散的负载型Ni基催化剂,提高催化剂加氢性能,采用共浸法制备了以炭改性Al2O3为载体(CCA)的Ni基催化剂,采用BET、XRD和H2-TPD对催化剂进行表征,以顺酐液相加氢为探针反应研究催化剂加氢性能。结果表明,通过共浸法同时引入活性组分Ni与炭助剂,经一次焙烧后即可获得活性组分Ni高度分散的负载Ni/CCA催化剂,在顺酐加氢反应中表现出高的γ-丁内酯选择性。     

Zr改性ASA分子筛催化剂对煤焦油加氢脱硫脱氮性能的影响

采用硫酸锆为锆源,对无定型硅铝分子筛(ASA)进行改性,利用等体积浸渍法制备Ni-Mo/Zr-ASA加氢催化剂,在悬浮床反应器上考察Zr改性前后催化剂的煤焦油加氢脱硫脱氮性能。采用XRD和 TEM等对改性前后催化剂进行表征。结果表明,经过Zr改性后,催化剂Cat-Zr-ASA上的金属活性组分在载体表面高度分散,颗粒均匀,粒径较小。与未改性的催化剂Cat-ASA相比,Zr改性后的催化剂Cat-Zr-ASA上加氢产物S含量和N含量分别降低了56.4%和63.8%。     

准东煤水热提质及废液催化气化特性研究

准东煤的碱金属(特别是Na、Ca)含量高,直接作为动力煤燃烧会导致严重的锅炉沾污、结渣。采用水热提质方法能够有效脱除煤中碱金属,同时还可改善煤质的理化特性,但水热提质也会产生大量废液,并导致有机质损失,原料的能量利用率低,限制了该方法的应用。针对上述问题,将水热提质技术与废液气化技术进行耦合,在水热反应釜和自制的两段式反应装置上开展了准东煤水热提质改性及衍生废液催化气化的试验研究,探究了提质后三相产物的分布特性及废液的催化气化特性。结果表明,随着水热温度的升高,煤样的固体回收率降低,废液中总有机碳(TOC)和气体产物显著增大,但至少有97.8%的碳元素分布在固相产物中。废液催化气化产生了富含CH_4、H_2的可燃气,最高占比达到70%。Ni/C催化剂中Ni元素对废液的气化起催化作用,催化效率随着水热温度、气化温度的升高而升高,随液时空速的升高而降低。优选的催化气化试验条件:Ni/C催化剂、水热温度为300℃、催化气化温度为350℃和液时空速为150 h-1。总之,水热提质-废液催化气化联用技术既可以实现煤质的改性,又回收了废液中的能量,能够为准东煤的清洁、高效利用提供新的思路。     

微波辐射下神府煤的催化加氢

以甲醇作为溶剂和萃取剂考察了在较温和的条件（140 oC,氢气初压0.7 MPa,微波辐射15 min）下活性炭、Ni和Pd/C催化剂对神府煤加氢反应的影响。结果表明：反应混合物在甲醇中的萃取率按非催化加氢< AC催化的加氢< Ni催化的加氢< Pd/C催化的加氢的顺序递增;通过GC/MS和FTIR分析可看出在不同反应条件下萃取物和萃余物组成的变化。     

Fe对肉桂醛选择性加氢催化剂Co/硅藻土的修饰作用

研究了Fe对负载型选择性加氢催化剂Co/硅藻土上肉桂醛加氢反应的修饰作用。实验结果表明,助剂Fe的加入对肉桂醛的活性和肉桂醇的选择性都有影响,但主要影响体现在催化活性上,选择性影响不明显。当n(Fe)∶n(Co)＜0.20,催化活性由60.69%明显提高到80.63%,再提高n(Fe)∶n(Co),活性又降低。结合XRD、SEM和正电子寿命谱等表征手段,结果发现,Fe对Co₃O₄晶体的完整程度产生影响,导致晶体缺陷数增加,Fe引入使催化剂在载体硅藻土表面分散性更好,分散的单层性更明显,负载在硅藻土上催化剂的晶粒粒径也有变小的趋势。     

Coal liquefaction using ore catalysts

Ores and ore concentrates containing minerals of Co, Mo, Ni, Fe, and other potentially active metals have been investigated as slurry catalysts for liquefaction of Blacksville mine, Pittsburgh seam, bituminous coal. The tests were conducted batchwise in a stirred autoclave for 30 min at 425°C and 13.79 MPa (2000 psig) hydrogen pressure according to a two-cycle scheme. In the first cycle, the reaction charge consisted of ground coal, catalyst, hydrogen, and SRC-II heavy distillate. The product of the first cycle was hot-filtered, and the liquid product served as a vehicle for the second cycle, which was otherwise run identically to the first. Reaction products from each cycle were analysed to determine conversion of coal, yield of liquids, liquid product viscosity, and group type (preasphaltene, asphaltene, and oil). Mixtures of ores containing iron pyrites and minerals containing other catalytically active transition metals were compared to pyrites alone and to a pulverized supported Co-Mo-alumina catalyst. An ore catalyst containing both Fe and Ni was superior to another that contained an equivalent mass of iron alone. The best ore catalysts tested, in terms of high liquid yields and low product viscosities, were mixtures of pyrites and molybdenum- and cobalt-containing ores. The latter yielded results that approached those obtained with an equivalent mass of cobalt and molybdenum on an alumina support.     

Improvement of oil yield and its distribution from coal extraction using sulfide catalysts

Extraction of Mae Moh lignite using toluene-tetralin mixture was performed in a batch reactor at a temperature range from 370 to 490 °C and under initial hydrogen pressure up to 12 MPa. Experiments were carried out to investigate the effects of temperature and initial hydrogen pressure on coal conversion, liquid yield and liquid composition. The effect of catalysts Fe₂S₃, Fe/Ni and Ni/Mo impregnated into activated carbon was also studied. In the absence of a catalyst, the oil yield decreased with temperature above 410 °C and the content of naphtha and kerosene increased while light gas oil and gas oil decreased with increasing temperature. The presence of catalyst would benefit the formation of lighter components, kerosene and light gas oil. Extraction in the presence of Ni/Mo catalyst, the liquid yield reached 64.6 wt% (daf) which included naphtha 2%, kerosene 72.8%, light gas oil 14.9%, gas oil 2.4% and long residue 7.9%. For GC-MS analysis, the fraction of kerosene was composed of tetralin, naphthalene, dodecamethyl-cycloheptasiloxane, methyl dodecanoate, tetradecamethyl-cycloheptasiloxane, ethyl dodecanoate, methyl tetradecanoate and dibutyl phthalate.     

Ni/W比对NiWCx催化剂加氢性能的影响

过渡金属碳化物具有类似贵金属的电子结构和加氢性能。采用等体积浸渍法制备了不同Ni/W比的NiW/γ-Al₂O₃催化剂,以程序升温碳化法转化为NiW碳化物后对芳烃模型化合物和低温煤焦油中分离所得芳烃组分进行加氢处理。催化剂的N₂吸附、XRD、H₂-TPR和SEM表征表明,Ni的添加促进了载体表面WO₃物种的分散和还原,抑制了WO₃晶体的团聚和大晶粒的生成。萘的加氢实验表明,Ni/W原子比为0.6时催化剂的活性最佳,而添加苯酚和吡啶后的模型油加氢过程中萘的转化率和十氢萘的产率均明显下降,Ni/W原子比为0.47和0.6的催化剂性能相近,煤焦油中芳烃组分加氢后Ni/W原子比为0.47的催化剂性能更优。结果表明,Ni和W均具有良好的加氢活性,但Ni耐杂原子性能较差,二者存在一个最佳的配比以使加氢性能更优。有杂原子化合物存在时,如煤基芳烃组分的加氢,Ni/W原子比为0.47的NiW碳化物催化剂具有更好的加氢性能。     

助剂改性FeOOH及其煤直接液化催化活性

采用共沉淀法分别引入Si、Al、La、Ca、Mg、Zr、Cu、Ni和Co 9种助剂元素对FeOOH催化剂改性,借助BET、XRD、SEM手段表征各助剂对催化剂微观结构、晶相和形貌的影响,在0.5 L高压釜内测试各催化剂对神东煤的直接液化催化活性。结果表明,引入Si、Al、Ca、Zr、Ni、Co能改善催化剂比表面积和分散度,分别提高煤液化油收率0.7～2.7个百分点;Ni和Co为最优助剂,Mg没有促进作用,Cu、La降低了油收率。研究表明,Al、Ca、Zr是通过结构支撑改善催化剂的织构性质,促进生成易于转化为活性相的小晶粒g-FeOOH,Ni、Co主要起到电子型助剂作用,通过强化对氢气的活化,促进煤的转化,提高油收率。     

Differential thermal analysis study of lignite hydrogenation

Several New Zealand lignites and three other coals have been compared by differential thermal analysis in hydrogen at a pressure of 8.0 MPa. Most coals showed two exothermic peaks at ≈350 and 500 °C, but the relative magnitude of the two peaks varied from one coal to another. Ion-exchanging one of the lignites with Zn, Fe, Ni, Pb and Sn reduced the temperature of the peak maximum. Both Fe and Sn are known to catalyse coal hydrogenation. The results show that nickel and lead warrant further investigation as potential catalysts for coal hydroliquefaction, since they reduced the reaction temperatures even more than Fe or Sn. The reaction of lignite with tetrahydronaphthalene, in the absence of hydrogen, has been shown to be endothermic; a factor of interest in the context of donorsolvent hydroliquefaction facilities.     

Gasification of coal impregnated with catalyst during pulverization: effect of catalyst type and reactant gas on the gasification of Shin-Yubari coal

Shin-Yubari coal was impregnated with several catalysts of different chemical types during pulverization. The resultant system was more homogeneous and reactive than systems prepared by impregnation of coarse coal. The relative activities of the catalysts were determined as a function of gasification temperature, catalyst loading and gasifying agent. The activity sequence in steam was K ? Ba ? Ni ? Fe ? coal ash. Each catalyst had a unique reaction profile. For example, using steam the specific rate or the rate per remaining fixed-carbon weight decreased with time for the iron-catalysed reaction, whereas it increased for the potassium-catalysed reaction. A similar order of activity was observed in carbon dioxide, but a different sequence was noted for the hydrogenation reaction. Transition metal catalysts were the most active. The hydrogenation reaction profiles were different from the oxidation profiles.     

煤焦油加氢裂化反应及其催化剂的研究

以煤焦油为原料,研究加氢裂化反应类型及反应产物油馏分的调制机理。以γ-Al2O3为载体,Mo、Ni为加氢活性组分,采用分步浸渍法制备负载型MoO3-NiO/γ-Al2O3加氢裂化催化剂。在高压反应釜上考察反应压力、反应温度对煤焦油加氢催化裂化反应的影响,比较了3种不同NiO质量分数的催化剂加氢活性,实验结果表明,NiO质量分数为3.68%的催化剂活性最好,并获得了低硫、低氮、低芳烃的反应产物油。     

Mo修饰的钼铁复合催化剂及其煤直接液化催化性能

分别在Fe催化剂制备的沉淀、氧化和干燥阶段引入Mo合成了五种Mo修饰的钼铁复合催化剂,调控了Mo和Fe的结合形式。利用XRD、SEM、TEM、BET、XRF、XPS和H₂-TPR对催化剂进行表征,在500 ml高压釜内进行神华上湾煤的直接液化实验。结果表明,钼铁协同催化作用促进了氢的活化和煤的分解,Mo修饰的复合催化剂的煤直接液化活性明显提高。Mo在催化剂表层分布有利于活性氢在工业循环溶剂和沥青类物质中的传递,促进沥青转化为油。Mo与Fe共沉淀会影响铁氧化物晶体形成和生长,使晶粒尺寸下降,比表面积和可还原度升高。Mo从氨水中引入形成均匀分散的小晶粒Mo-Fe复合化合物,液化油产率提高4.4%。浸渍引入Mo不改变铁氧化物结构,但Mo富集于催化剂表面提高了与反应物的碰撞概率,液化油产率提高5.0%。     

Hydrogenation of a brown coal pretreated with water-soluble nickel/molybdenum and cobalt/molybdenum catalysts

Loy Yang brown coal treated with cobalt acetate/ammonium molybdate (Co/Mo) gave lower conversions than the very high values obtained for the same coal treated with nickel acetate/ammonium molybdate (Ni/Mo) when reacted with hydrogen at 400°C. The difference in conversions obtained between the two catalyst systems decreased with increasing time. Addition of sulphur as carbon disulphide (CS₂) eliminated the difference between the Co/Mo and Ni/Mo catalyst systems, but neither system was more active than a sulphided Mo catalyst. Addition of a hydrogen donor solvent, tetralin, to a reaction in the absence of sulphur decreased conversion for the Ni/Mo catalysed system, but increased that for the Co/Mo system. The order of activity in reactions without solvent or added sulphur for the coal treated with the individual metals was CoMo < Ni. In the presence of sulphur the order was Co Ni < Mo; the addition of sulphur led to no significant improvement with Co catalysts.