共查询到17条相似文献,搜索用时 125 毫秒
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氢转移对煤的加氢液化至关重要,理解氢转移机理对于改善煤液化过程具有重要意义。在微型反应釜中通过考察氢气的溶解、溶剂类型以及不同类型催化剂对煤高温快速液化的影响,揭示了煤高温快速液化过程中单原子氢和双原子氢的转移机理。结果表明,在以四氢萘、氢气为条件的高温快速液化过程中,主要的活性氢来源于溶剂所提供的单原子;在以四氢萘、氮气为条件的高温快速液化过程中,不同催化剂对溶剂提供单原子氢的影响不同。在以四氢萘和萘、氢气为条件的高温快速液化过程中,双原子氢基本未参与液化反应,溶解并不是其参与液化反应的主要影响因素。以萘为溶剂、氢气气氛下的高温快速液化过程中,双原子氢参与反应需要一定的时间。在以萘或四氢萘、氢气为条件的高温快速液化过程中通过加入一定量的催化剂,可以促使双原子氢快速参与反应。 相似文献
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为研究胜利褐煤在初始阶段的煤液化反应动力学,在可快速升降温的微型高压釜中对胜利褐煤进行了加氢液化反应,得到了反应初期煤液化参数,并对胜利褐煤加氢液化反应初期的动力学行为进行分析。结果表明,虽然反应器升温速度较快,但到达反应温度时,仍有一定量的煤发生了转化,在反应温度440℃、反应时间为0时转化率达到28.12%;在较低温度下,胜利褐煤只发生了部分热解反应,反应后期几乎不再转化,在380℃、反应10 min后转化率已达28%,后续基本不变;随着反应温度的升高,反应转化率、油水产率、气产率等指标增大,反应前10 min增速较快,10~25 min时反应速率减缓,主要是沥青烯组分作为中间产物不断向油转化,速率较低。 相似文献
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以杨村煤为例,在490℃和2倍四氢萘溶剂的条件下,反应仅5min煤直接液化总转化率就达到84.47%,表明煤在直接液化的过程中具有初始高反应活性的特点。在纯氢气气氛下随着初始压力从1.5MPa增大到7MPa,转化率从66.38%上升为83.27%,表明压力大小对煤液化转化率有较大影响。1.5MPa下溶煤比提高到4:1以后,转化率增大到79.0%就不再增长,表明用添加过量供氢溶剂的方法弥补由于降低系统压力所带来的转化率损失不可行。 相似文献
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采用平衡液相取样法气体溶解度测定装置测定了氢气在萘中的溶解规律,并采用间歇式微型反应釜研究了氢气在无催化煤液化中的反应机理.结果表明:1)氢气在萘中的溶解随着温度和压力的升高而增加,溶解速率先快后慢,在5min时达到最大溶解量的76.21%左右,直到30min达到平衡;2)在萘溶剂的无催化煤液化反应中,氢气的溶解不是控制步骤,溶解氢参与液化反应的速度才是控制步骤;3)在较短时间的萘溶剂无催化煤液化时,氢气在萘溶剂中的预溶解提高了无催化煤液化的总转化率,其主要原因是部分预溶氢提前活化,使得煤液化反应初期活性氢增加;4)在较长时间的萘溶剂无催化煤液化时,预溶氢对总转化率的提高很小,但促进了液化产物的进一步裂解加氢轻质化. 相似文献
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溶剂组成对褐煤催化液化的影响 总被引:1,自引:0,他引:1
本文采用60ml微型高压釜,以杂酚油为溶剂,在氨初压6.0MPa,反应温度400℃,反应时间30min的条件,以四氢萘,邻苯二酚为模型化合物,考察了溶剂中供氢组分和酚类物质对先锋褐煤催化液化的影响.实验结果表明,供氢组分对液化转化率和油品产率皆有重要作用;酚类物质对液化转化率影响较小,但能改变液化产物之间的分布,催化剂活性是随溶剂中供氢组分和酚类物质百分含量的改变而发生变化. 相似文献
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通过正交试验考察了蔗渣在水与四氢萘混合溶剂中液化过程的5个因素对蔗渣转化率的影响.蔗渣在混合溶剂中的优化工艺为:反应温度270 ℃、反应时间30 min、固液比(蔗渣与溶剂质量比)1:6、碱浸预处理NaOH用量4%、四氢萘用量(占总溶剂质量分数)50%.各因素的影响次序:NaOH用量>反应温度>四氢萘用量>固液比>反应时间.在此工艺条件下,蔗渣转化率可达到97.9%.实验结果表明,四氢萘部分取代液化溶剂中的水,可以有效提高蔗渣液化效率,同时降低反应温度及压力,促进实验操作条件的改善. 相似文献
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Single and multi-stage liquefaction of Shenhua (SH) bituminous coal and re-liquefaction of its liquefaction residue (SHLR) were carried out in an autoclave reactor to investigate the essential approach for promoting oil yield and conversion in SH coal direct liquefaction (SHDL). The multi-stage liquefaction includes pretreatment, keeping the reactor at 250 °C for 40 min before heating up to the reaction temperature, and two-stage liquefaction processes consisting of low temperature stage, 400 °C, and high temperature stage, 460 °C. The results show that the pretreatment has slight effect on oil yield and conversion of SHDL, especially for liquefaction at 460 °C. There is a positive function of two-stage liquefaction in shortening reaction time at high temperature. Increasing ratio of solvent to SHLR can promote the oil yield and abate reaction condition in SHLR re-liquefaction, that is, it can promote the conversion from preasphaltene and asphaltene to oil. The primary factor to inhibit coal liquefaction is the consumption of hydrogen free radical (H·) from solvent or H2 and condensation of free radicals from coal pyrolysis after a period of reaction. So the essential approach for increasing oil yield and conversion of SHDL is to provide enough H· to stabilize the free radicals from coal pyrolysis. 相似文献
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通过对四十余种常见煤液化模型化合物键能的分类、排序与分析,发现仅桥键的热致裂解远不足以让煤直接液化的转化率达到常见的70%以上的转化率.除了由于煤的高芳香性导致共振稳定和反应时间延长导致活化能量积累作出贡献以外,还有三个因素对桥键的广泛断裂和煤液化的高转化率作出了贡献,即溶剂、氢压和矿物质等催化剂. 相似文献
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Model compound studies have shown that 1,2,3,4-tetrahydroquinoline is an exceptionally good coal solvent. In the pure compound, subbituminous coal conversion to THF-soluble products approaches 100% under relatively mild reaction conditions. The effectiveness of tetrahydroquinoline for coal conversion appears to be related to its concentration relative to coal. The unique behaviour of tetrahydroquinoline is ascribed to its being a highly active H-donor; the fact that it is regenerable under reaction conditions by the reaction of hydrogen and quinoline; and that its polarity allows penetration of the coal structure and aids in dispersion of the dissolved coal. It has been found that, during reaction with coal, tetrahydroquinoline and other nitrogen compounds undergo extensive condensation reactions which result in an increase in the nitrogen content of the high boiling and non-distillable liquefaction products. 相似文献
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Coals were liquefied in a 50 ml autoclave using hydrogen produced from methanol with decomposition and hydrogenation catalysts under various conditions. The conversion increased with increasing reaction temperature and time. This reaction is more suitable for the liquefaction of lower-rank coals. The hydrogen pressure had little effect on the conversion in the range of the ratio of methanol to coal of 2 g/g. The use of a solvent is very effective in increasing the liquefaction, especially at short times. 相似文献