共查询到18条相似文献,搜索用时 171 毫秒
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采用中和成胶法,以偏铝酸钠、硫酸铝等为原料,考察了成胶温度、成胶p H值、助剂等条件对合成氧化铝产品性能的影响。结果表明:升高成胶温度,氧化铝产品的结晶度随之增高,比表面积呈先增大后减小的趋势,孔容、孔径增大,在成胶温度为70℃时产品的最可几孔径最大。随成胶pH的升高,氧化铝产品的比表面积逐渐减小,pH=7时以小孔为主,pH=8时孔容增至最大,孔分布向大孔方向偏移,继续增高p H值孔容和大孔比例均减小。在成胶体系中引入2%的P、F、Si作为助剂均可有效提高氧化铝的孔径,助剂F和Si会使氧化铝的比表面积和孔容有所减少,而P会显著提高氧化铝的比表面积和孔容。加入0.2%~1%的B_2O_3作为助剂后,产品的孔径分布向大孔方向显著偏移。 相似文献
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γ-氧化铝载体合成的研究 总被引:7,自引:0,他引:7
对以氯化铝和氨水为原料制备氧化铝的过程进行了考察,着重考察中和的温度、pH值、反应物浓度和老化条件对γ-Al2O3对氧化铝孔结构的影响。在试验范围内,氯化铝浓度对氧化铝孔容和比表面积影响不大,提高中和温度,氧化铝的孔容和比表面积增加高,高pH有利于提高孔容和比表面积;老化时间和温度对氧化铝孔结构没有明显的影响。 相似文献
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采用异丙醇铝水解法制备氧化铝,考察了多种因素对氧化铝物化性质的影响。用X射线衍射、氮物理吸附、扫描电镜等方法分析了所得样品的晶相结构、孔结构以及微观形貌。试验结果表明:异丙醇铝在不同条件下水解均能制备出高纯的拟薄水铝石;提高水解温度有利于提高所制备氧化铝的孔径以及孔容;低水解液浓度有利于制备大孔容的氧化铝,而高水解液浓度有利于制备小孔容的氧化铝;水与异丙醇铝比例在2:1~4:1时拟薄水铝石和氧化铝比表面积和孔容达到最大;水解时间为3~4 h是制备高比表面积和大孔容拟薄水铝石和氧化铝的最佳时间。 相似文献
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本文对以工业ZrOCl2为原料,NH3·H2O为沉淀剂合成ZrO2进行了研究,重点考察了ZrOCl2溶液浓度、NH3·H2O浓度、沉淀pH值、沉淀及老化温度等因素对所制备的ZrO2表面积和孔容的影响,从而得出了一定的规律。 相似文献
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《化学工程》2015,(12):1-5
以5种市售拟薄水铝石(PB)为氧化铝前驱体,硝酸为胶溶剂,采用海藻酸辅助溶胶-凝胶法制备了球形氧化铝颗粒,采用静态氮气吸附-脱附仪与智能颗粒强度试验机进行表征,考察了制备过程中拟薄水铝石的胶溶指数、酸处理浓度及恒温恒湿过程对球形氧化铝颗粒物性的影响。实验结果表明:拟薄水铝石的胶溶指数是其粘结性能的主要指标,也是影响γ-Al_2O_3孔结构与强度的关键因素,随着胶溶指数的增大,γ-Al_2O_3比表面保留率逐渐减小,孔容与孔径保留率先减小后增大,强度值逐渐增大;酸处理浓度对γ-Al_2O_3物性的影响规律为随着酸处理浓度的提高,孔容、孔径减小,强度及比表面增大;经过恒温恒湿过程,在保证孔结构的同时能够极大地提高γ-Al_2O_3颗粒的强度,优化的恒温恒湿时间为4 h。 相似文献
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介绍了球形氧化铝的各种制备工艺及成形方法,并以油柱成形法制备球形氧化铝。利用低温液氮吸附仪、压汞仪以及智能强度测定仪对其物化性质进行了测定,重点考察了不同铝源合成的水合氧化铝、加料方式、扩孔剂和胶溶剂用量对球形氧化铝性质的影响。实验结果表明,制备水合氧化铝的铝源是影响球形氧化铝的重要因素;并流加料方式能制得大孔容、低表观密度、高强度的球形氧化铝;球形氧化铝的制备过程中,要制得适合于油柱成形的铝溶胶,胶溶剂加入量有最佳的用量范围,胶溶剂用量愈大,球性氧化铝的强度、比表面、孔容愈大,而孔径却随之变小;活性炭粉能有效地提高球形氧化铝的压汞孔容。 相似文献
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煤拔头中低温快速热解烟煤半焦的孔隙结构 总被引:1,自引:0,他引:1
利用喷动载流床模拟煤拔头工艺,在550, 650, 750和850℃热解温度下对大同烟煤进行热解得到拔头半焦. 采用氮吸附法对该烟煤及其半焦的孔隙结构进行了研究. 结果表明,拔头半焦的孔隙发达度都弱于原煤;由低到高4个热解温度下挥发分析出率(Y)依次为7.89%, 21.79%, 22.12%, 39.33%,中孔尺寸随Y增加而减小,微孔和大孔尺寸及总孔体积和总孔比表面积基本随Y增加而增加;550℃时挥发分的析出对孔隙结构的发展无明显有利影响. 从原煤到半焦(热解温度由低到高),样品满足BET吸附等温式的相对压力范围依次为0.101~0.351, 0.093~0.201, 0.072~0.152, 0.032~0.053, 0.058~0.108,BET比表面积与NLDFT总孔比表面积变化趋势一致. 相似文献
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Mesoporous alumina, TUD-1, was prepared via a sol-gel process by using tetraethylene glycol (TEG) as template. The effect
of TEG and solvents on the pore structure of the final products was studied. A mechanism using non-surfactant template was
proposed. It was found that TUD-1 has amorphous framework, high surface area, large pore volume and narrow pore size distribution
together with high thermal stability upon prolonged heat treatment at high temperatures, which is essential for applications
in adsorption and catalysis. 相似文献
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Mesoporous alumina, TUD-1, was prepared via a sol-gel process by using tetraethylene glycol (TEG) as template. The effect of TEG and solvents on the pore structure of the final products was studied. A mechanism using non-surfactant template was proposed. It was found that TUD-1 has amorphous framework, high surface area, large pore volume and narrow pore size distribution together with high thermal stability upon prolonged heat treatment at high temperatures, which is essential for applications in adsorption and catalysis. 相似文献
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Joo Hyun Kim Kyeong Youl Jung Kyun Young Park 《Journal of Industrial and Engineering Chemistry》2012,18(1):344-348
Mesoporous alumina particles were prepared by using a spray pyrolysis process of aluminum nitrate precursor using cetyltrimethylammonium bromide (CTAB) as a structure-directing agent. The effects of ammonium hydroxide, urea, and drying-control-chemical agent (DCCA) on the particle morphology and pore properties of alumina particles were studied by means of N2 physical adsorption, transmission electron microscopy (TEM), and small-angle X-ray diffraction (SAXS) analysis. It was found that using urea rather than NH4OH in the spray pyrolysis is effective to increase the surface area of alumina with well-organized uniform pores. The addition of NH4OH led to decrease the surface area as well as the pore regularity. Using both DCCA and urea was a helpful way to improve the surface area, the pore volume, and the pore size distribution of alumina synthesized by spray pyrolysis. The prepared alumina particles had a broad SAXS peak without further reflection peaks indicating hexagonal or cubic symmetry. According to TEM analysis, a long-range ordering of mesopores was not observed. More details on the texture properties and the morphology of alumina particles prepared by with changing the kinds of additives in spray solution were discussed. 相似文献
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利用煤气化焦油渣为原料进行活性炭制备实验研究,对炭化过程焦油渣孔结构和表面特征进行研究,采用N2吸附/脱附等温实验和表面分形理论研究炭化对焦油渣孔结构和表面特征的影响。结果表明:炭化物的吸附等温线倾向于表征微孔吸附特征的Ⅰ类吸附等温线;炭化物中具有发达的微孔结构、过渡孔结构和极不发达的大孔结构;随着温度和升温速率的提高,微孔结构先增加后又逐渐发展为过渡孔和大孔;对炭化物表面的分形特征进行研究发现,表面分形维数与BET比表面积、总孔容、平均孔径不存在直接关系,但是与微孔面积占比和微孔容积占比存在较好的一致性;焦油渣在炭化处理过程中随着温度的升高和升温速率加快,经历了“立体发展-逐渐衰落”的过程。当炭化终温850℃、升温速率20℃/min时,可以得到最优的活化前体。 相似文献
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The pore volume, surface area and compressibility of eleven Canadian coals, varying in rank from lignite to semianthracite, have been determined by mercury porosimetry, gas adsorption method and relations derived from helium and mercury densities. The total pore volume was measured in the diameter range of 0.2 nm–2.98 μm, which was subdivided into two groups, namely the micropore region (< 0.0036 μm) and the combined meso- and macropore region (0.0036–2.98 μm). It has been determined that the porosity of the eleven coals studied varies from 2 to 39%. It has been found that the total pore volume, micropore volume, surface area and the apparent compressibility of these coals decrease with increase in the carbon content, or the rank of the coals. The effect of the total pore volume, micropore volume and surface area on chemical reactivity of the coal is discussed separately. A good correlation was obtained between the carbon content and helium density of the coal after correction is made for the mineral content. 相似文献