共查询到20条相似文献,搜索用时 78 毫秒
1.
以中和法、水热法、醇铝法和铝粉盐酸回流法合成的氧化铝前驱体为原料分别制备球形氧化铝载体(记为ZH、SR、ST和SOL),通过强度仪、X射线荧光光谱仪(XRF)、低温氮气吸附-脱附、扫描电镜(SEM)、氨程序升温脱附(NH3-TPD)等手段对氧化铝载体进行表征,以丙烷脱氢为探针反应研究了氧化铝的制备方法对催化剂(Pt-Sn-K/Al2O3)脱氢性能的影响。实验结果表明:不同方法合成的氧化铝前驱体均制备出高强度的球形氧化铝载体,其中水热法和醇铝法制备的载体还具有较大的孔容和适中的比表面积;前驱体的制备方法对催化剂的酸性影响较大,中和法制备的氧化铝载体制备的催化剂主要是弱-中强酸中心,其他方法制备的氧化铝载体制备的催化剂为弱酸中心,催化剂酸量由大到小的顺序为ZH-CAT、SOL-CAT、ST-CAT、SR-CAT;评价结果表明,醇铝法和水热法制备的载体应用于丙烷脱氢催化剂表现出良好的性能,相当于甚至优于工业剂水平。 相似文献
2.
3.
通过水热法合成了氮掺杂的石墨烯(Graphene-N),并还原得到了氮掺杂的石墨烯基铂催化剂(Pt/Graphene-N),利用X射线衍射(XRD)以及扫描电子显微镜(SEM)进行了材料分析,并借助电化学测试对比未进行氮掺杂的催化剂。试验数据表明:Pt/Graphene-N电化学活性面积相比于Pt/Graphene提高了8.1%,其甲醇氧化峰电流提高了56.3%,表明氮掺杂能够大幅提升甲醇氧化性能。 相似文献
4.
以L-赖氨酸为模板剂,采用沉淀法制备了BiOCl催化剂,对催化剂进行了X射线衍射、N2吸附-脱附和H2-TPR等表征,并测试了BiOCl催化剂对丙烷氧化脱氢制丙烯反应的催化性能。结果表明,制备的BiOCl催化剂为四面体结构,500 ℃焙烧3 h后,催化剂比表面积为11.2 m2·g-1,未完全还原氧物种的含量较多。随着反应温度升高,丙烷转化率和丙烯选择性增加,丙烷转化率为20%时,丙烯选择性达64.5%。 相似文献
5.
自2016年Hermans课题组发现六方氮化硼(h-BN)在丙烷氧化脱氢制丙烯(ODHP)反应中优异的烯烃选择性,各类硼基材料引起了研究者强烈的研究兴趣并广泛地用于ODHP反应。与传统金属与金属氧化物基催化剂不同,非金属硼基催化体系能够有效抑制CO x 等过度氧化产物,提高烯烃产率,具有较广阔的工业应用前景。本综述对硼基丙烷氧化脱氢催化剂从催化剂的设计、合成策略和反应性能等方面进行了系统地讨论,阐明了催化剂的构效关系;总结了反应路线、关键中间体、决速步以及催化动力学行为,加深了硼基催化剂催化丙烷氧化脱氢活性位点和机理的理解。指出三配位B—O/B—OH活性位点的有效构建及实现表面与气相自由基反应的协同催化是提高硼基催化剂丙烷脱氢性能的关键。基于目前的研究现状和存在的问题,对硼基催化剂体系研发前景和未来工业化应用进行了展望。 相似文献
6.
7.
以人工合成的3种不同层板组成的层状双羟基金属氢氧化物MgAl-CO3-LDHs、CoAl-CO3-LDHs和NiCr-CO3-LDHs为载体,以偏钒酸钠NaVO3为柱撑剂和钒前体,采用离子交换法制备了钒柱撑的催化剂样品(MgAlVO、CoAlVO和NiCrVO),通过XRD、FTIR、XPS和Raman等手段表征了样品的物相、钒物种的存在形态以及钒的价态,以丙烷氧化脱氢制丙烯为模型反应,表征了所制备的催化剂样品的催化性能,着重探讨了LDHs载体的层板组成以及钒的含量对催化剂样品中的钒氧物种存在形态及其丙烷氧化脱氢催化性能的影响。结果表明:以20%理论含量的钒柱撑MgAl-CO3-LDHs所制备的催化剂样品20%MgAlVO对丙烷氧化脱氢反应的催化性能较好,当反应温度为560℃时,丙烯收率可以达到11.3%,Raman光谱显示该催化剂样品中的钒以Mg3V2O8和α-Mg2V2O7两种形式共存,且晶格氧O2-和吸附氧O-所占的比例较为均衡,有利于获得较好的丙烷氧化脱氢催化性能,而在同样条件下制备的催化剂样品20%CoAlVO和20%NiCrVO中的钒物种只观察到分别以Co3V2O8和Ni3V2O8存在的正钒酸盐,前者对丙烯的收率不到8%,后者甚至完全得不到丙烯。 相似文献
8.
9.
以浸渍法制备VMo/γ-Al2O3和VMoMg/γ-Al2O3催化剂,考察其催化丙烷氧化脱氢制丙烯的反应活性,采用XRD、UV-Vis DRS和In suit IR对催化剂进行表征。结果表明,V负载质量分数为3%、Mo负载质量分数为7%时的3V7Mo/γ-Al2O3催化剂表现出较好的催化性能;添加Mg后催化剂的催化性能有所改善,反应温度500 ℃时,丙烷转化率为18.19%,丙烯选择性74.76%。丙烷和丙烯在3V7Mo/γ-Al2O3和3V7Mo4Mg/γ-Al2O3催化剂上吸附后,C—H键的H与催化剂活性中心的晶格氧发生作用形成H—O键,且3V7Mo4Mg/γ-Al2O3催化剂上出现C—O键的温度比3V7Mo/γ-Al2O3催化剂高,表明加入Mg有利于提高丙烯选择性。 相似文献
10.
11.
Metal pyrophosphates (M–P2O7, where M is V, Zr, Cr, Mg, Mn, Ni or Ce) have been found to catalyze the oxidative dehydrogenation of propane to propene. The reaction was conducted at 1 atm, 450–550°C and feed flowrate of 75 cm3/min (20 cm3/min propane, 5 cm3/min oxygen and the balance is helium). All catalysts showed increase in degrees of conversion and decrease in olefins selectivity with increase in reaction temperature. At 550°C, MnP2O7 exhibited the highest activity (40.7% conversion) and total olefins (C3H6 and C2H4) yield (29.3%). The other catalysts, indicated by their respective metals, may be ranked (based on olefins yield) as V (16.9%) < Cr (17.5%) < Ce (25.1%) < Zr (26.2%) < Ni (26.8%) < Mg (27.9%). The reactivity of the lattice oxygen was estimated from energy of formation of the corresponding metal oxides. Correlation between the selectivity to propene and the standard energy of formation was attempted. Although there was no clear correlation, the result suggested that the lattice oxygen play a key role in the selectivity-determining step. 相似文献
12.
Chromium Oxide Supported on Mesoporous SBA-15 as Propane Dehydrogenation and Oxidative Dehydrogenation Catalysts 总被引:3,自引:0,他引:3
The catalytic activity and selectivity of Cr2O3 supported on mesoporous SBA-15 for non-oxidative and oxidative dehydrogenation of propane by O2 and CO2 have been studied and compared with those of Cr2O3/ZrO2 and Cr2O3/-Al2O3 catalysts. Cr2O3/SBA-15 and Cr2O3/ZrO2/SBA-15 are more selective to propene and more resistant to coking in comparison with Cr2O3/ZrO2 and Cr2O3/-Al2O3 for non-oxidative dehydrogenation of propane. In oxidative dehydrogenation of propane by O2 and CO2, Cr2O3/SBA-15 also displays better activity, selectivity and stability than the other two supported catalysts. The propane conversion and propene yield on Cr2O3/SBA-15 catalyst for oxidative dehydrogenation of propane by CO2 at 823 K reach 24.2 and 20.3%, respectively. XPS and TG/DTA have been used to characterize the catalysts before and after reaction. The differences in catalytic behavior of various supported Cr2O3 catalysts in the reactions have been discussed on the basis of the characterization results. 相似文献
13.
Shigeru Sugiyama Takuya Hashimoto Naoya Shigemoto Hiromu Hayashi 《Catalysis Letters》2003,89(3-4):229-233
In order to examine the mobility of lattice oxygen in magnesium vanadates, these catalysts were employed for the oxidative dehydrogenation of propane in the absence of oxygen for 2.25h, followed by the addition of gaseous oxygen into the feedstream. Depending on the degree of the abstraction of lattice oxygen from these catalysts during the oxidation in the absence of the gaseous oxidant, oxygen in the effluent was detected at approximately 1.4 and 9min with Mg3V2O8 and Mg2V2O7 respectively, after the addition of gaseous oxygen under the present reaction conditions. However, no oxygen was detected with MgV2O6 even after 18.5min from the addition of gaseous oxygen. 51V MAS NMR was also employed for the observation of redox behaviors of vanadium species in these catalysts during the reaction. 相似文献
14.
15.
Highly active Ce-based monolithic catalysts for oxidative dehydrogenation of ethane with CO2 were prepared and characterized by various techniques. The high oxidation state Ce4+ species had higher catalytic activity than the Ce3+ species in the monolithic catalysts. The Ce4+ species was reduced to Ce3+ species in the ethane dehydrogenation process, and the reduced Ce species was reoxidized to the Ce4+ species by treatment with CO2 at 750 °C, the Ce redox cycle played an important role in the catalyst’s high activity. 相似文献
16.
丙烷氧化脱氢负载型催化剂的研究 总被引:2,自引:1,他引:2
制备了V2O5/TiO2和V2O5/TiO2 ZrO2负载型催化剂,并对催化剂进行了反应评价和BET、XRD、H2-TPR表征。通过研究验证了利用溶胶凝胶技术制备的负载TiO2催化剂有较好的低温反应活性,在250℃下反应得到2 2%的丙烯收率。对TiO2进行离子掺杂后催化剂活性组分能够和混合氧化物载体进行键合,形成稳定的O—V—Zr键和O—V—Ti键,使催化剂的还原温度从480℃增加到650℃,在350℃下反应得到12%的丙烷转化率和55%的丙烯选择性。 相似文献
17.
Daniell W. Ponchel A. Kuba S. Anderle F. Weingand T. Gregory D.H. Knözinger H. 《Topics in Catalysis》2002,20(1-4):65-74
A series of ceria-supported vanadium catalysts was prepared via impregnation of the support with an ammonium metavanadate solution. The 723 K calcined samples were tested for propane oxydehydrogenation (ODH) activity and selectivity. The sample exhibiting the highest propane conversion was found to be the ceria support material itself, although this showed essentially no selectivity towards propene. An optimum propene yield of 4.2% was obtained at 673 K for the 6 wt% V2O5-CeO2 sample. Conversion decreased with increasing V loading which was attributed to the formation of cerium vanadate (CeVO4). This phase was found in all samples after calcination, its abundance rising in proportion to the V loading. In the 6 wt% V2O5 catalyst hydrated surface VOx species were present, although they underwent conversion to CeVO4 at temperatures above 573 K. The low reducibility of these surface vanadates was linked to the oxidation activity. It is inferred that surface polyvanadate species are responsible for the selective ODH of propane with V-O-V and/or V-O-Ce being the active oxygen species. 相似文献
18.
Qingjun Zhu Makoto Takiguchi Tohru Setoyama Toshiyuki Yokoi Junko N. Kondo Takashi Tatsumi 《Catalysis Letters》2011,141(5):670-677
Abstract
Cr/silicalite-1 and Cr/H[B]MFI catalysts were prepared by the impregnation method, and Cr/H[B]MFI were further treated by steaming. The catalysts were employed for the oxidative dehydrogenation of propane to propylene with CO2 as the oxidant. Cr/H[B]MFI showed significantly higher catalytic activity than Cr/silicalite-1, and steamed Cr/H[B]MFI was superior in the reaction stability to Cr/H[B]MFI. The nature of the supported chromium species have been characterized by a number of physicochemical techniques, such as Raman, UV–vis and NMR. It is concluded that the steaming led to the auto-reduction of some Cr6+ to Cr3+, and resultant Cr3+ species might be located near the boron center in the borosilicate framework to counterbalance the negative charge of the framework. The transformation of Cr6+ species to Cr3+ species, facilitated by the steaming process and the presence of boron in the catalyst, is responsible for the enhanced stability of oxidative dehydrogenation of propane to propylene with carbon dioxide as the oxidant. 相似文献19.
Yong-Mei Liu Lu-Cun Wang Miao Chen Jie Xu Yong Cao He-Yong He Kang-Nian Fan 《Catalysis Letters》2009,130(3-4):350-354
Doughnut-like structured CeNiO, prepared by a novel oxalate gel co-precipitation method, exhibited significantly higher activity in oxidative dehydrogenation of propane at a temperature as low as 275 °C than conventional catalysts such as VMgO. It is suggested that oxygen vacancy formed in CeO2 lattice due to the incorporating of Ni atoms adsorbs and activates the molecular oxygen to form active oxygen species. The superior performance for propane oxidative dehydrogenation over CeNiO catalyst can be attributed not only to the properties of the CeNiO catalyst but also to its unique doughnut-like structure. 相似文献