二甲醚燃烧用掺杂钡、镍六铝酸盐催化剂的研究

二甲醚是易液化，便于运输，清洁化的新能源。当作为燃料使用时，采用催化燃烧的方法能使得燃烧的起燃温度降低和提高燃烧转化率，克服了普通燃烧的缺点，实现了清洁燃烧。对二甲醚催化燃烧用的催化剂BaNiAl11O19-δ进行了制备与研究。采用溶胶-凝胶法制备六铝酸盐催化剂BaNiAl11O19-δ,考察其对新能源二甲醚催化燃烧反应的活性，并用TG—DTA对催化剂的性质进行考察。结果表明，加入经800℃焙烧4h后又在1200℃焙烧了2h的催化剂，比未加催化剂的燃烧体系T10降低了50℃。用溶胶一凝胶法制备的六铝酸盐催化剂BaNiAl11O19-δ对二甲醚催化燃烧反应具有较高的催化活性。     

The effect of magnesium compounds (MgO and MgAl2O4) on the synthesis of Lanthanum magnesium hexaaluminate (LaMgAl11O19) by solid-state reaction method

In the present study, the lanthanum magnesium hexaaluminate (LaMgAl₁₁O₁₉)(LaMA) powder was synthesized by the solid–state reaction method using two types of magnesium compounds, including magnesium oxide (MgO) and magnesium aluminate (MgAl₂O₄) spinel (MAS). The effect of substitution of magnesium oxide with MAS on the synthesis temperature, intermediate compounds and morphology of synthesized powders were investigated. The microstructural results showed that the intermediate compounds of lanthanum aluminate (LaAlO₃), aluminum oxide and MAS were formed in the presence of magnesium oxide, whereas in the latter case, the LaAlO₃ intermediate phase was not observed and La₄Al₂MgO₁₀ was formed at about 810 °C. Also in both cases, a single LaMA phase with the platelet-like morphology was formed. The thickness of the LaMA platelets decreased from 300 nm to 125 nm and the synthesis temperature increased from 1330 °C to 1355 °C, by replacing MgO with MAS.     

Fe‐substituted Ba‐hexaaluminates oxygen carrier for carbon dioxide capture by chemical looping combustion of methane

Fe‐substituted Ba‐hexaaluninates (BFA‐x (x = 1–3), x indicates Fe content) oxygen carrier (OC) were found to exhibit excellent sintering‐resistance under cyclic redox atmosphere at 800°C thanks to the reservations of the structure during the CH₄ reduction step, thus preventing the agglomeration of particles during the subsequent reoxidation step. Lattice oxygen highly active for the total combustion of CH₄ was observed in the hexaaluminate structure and its chemical state was influenced by Fe content. The highest amount of active O coordinated with Fe³⁺ in the mirror plane (O‐Fe³⁺(M)) for the total combustion was reacted (0.77 mmol/g) for BaFe₃Al₉O₁₉ hexaaluminate OC. As a result, it exhibited the best reactivity with the CH₄ conversion of 83% and CO₂ selectivity of 100%. Moreover, superior regeneration and recyclability was also obtained, which originated from the fully recovery of O‐Fe³⁺(M) in the hexaaluminate structure. © 2015 American Institute of Chemical Engineers AIChE J, 62: 792–801, 2016     

不同方法制备K2MnAl11O19六铝酸盐催化剂及其甲烷的燃烧活性

介绍了共沉淀法和异丙醇盐水解法制备了六铝酸盐催化剂K2MnAl11O19,用XRD、BET、SEM和TG-DTA技术及甲烷燃烧活性对催化剂进行了表征和活性验证。结果表明,两种方法所制备的催化剂经1200℃焙烧4h后均可以形成完整的六铝酸盐晶型,同时都具有高的催化性能和高温稳定性,其中异丙醇盐水解法制备的K2MnAl11O19催化剂具有较高的比表面积和甲烷催化燃烧活性。     

新型功能材料六铝酸盐复合氧化物研究进展

综述了新型功能材料六铝酸盐复合氧化物的制备方法、晶体结构及应用研究进展.     

Synthesis and properties of lanthanum hexaaluminate ceramic La1−xCaxAl11−y−zMgyTizO18

The aim of the present work is to obtain ceramic materials with a hexagonal structure and high density, hardness and mechanical strength at lower synthesis temperature. Ceramic samples with nominal composition La_1−xCa_xAl_11−y−zMg_yTi_zO₁₈ (x=0–1; y=0–3; z=0–3,5) are prepared. The samples are sintered at temperature 1500 °C by one-stage and two-stage ceramic technology. By X-ray diffraction and scanning electron microscopy, predominant phase LaAl₁₁O₁₈ and second phases LaAlO₃ and -Al₂O₃ are identified. Ceramic materials are characterized with high physico-mechanical properties and may be find application for production of mill bodies and materials for immobilization of nuclear waste.     

反应条件下的水蒸气处理对复合氧化物催化剂甲烷催化燃烧的影响

对水热法制备的LaMnAl11O19-α（LMA）催化剂和微乳液法制备的Ce0.5Ba0.5MnAl11O19-α（CBMA）催化剂进行了100h的甲烷催化燃烧活性试验,考察了反应条件下的水蒸气处理对催化剂的结构和甲烷催化燃烧活性的影响。结果表明：反应条件下的水蒸气处理促进了水热法制备的LMA催化剂中的六铝酸盐相晶粒长大,比表面积降低,从而引起活性下降。对微乳液法制备的CBMA催化剂,反应条件下的水蒸气处理使得催化剂中的γ-Al2O3转化为α-Al2O3从而引起比表面积的大幅度降低,但催化活性没有出现明显变化,仍保持着较高的甲烷燃烧活性。     

A comparative study of the catalytic performance of nickel supported on a hibonite-type La-hexaaluminate synthesized from aluminum saline slags in the dry reforming of methane

In this work, a hibonite-type Ni/La-hexaaluminate (Ni/LHA) synthesized from an industrial waste is used and compared as catalyst in the dry reforming of methane (DRM) at 973 K. The structure, catalytic behavior, and stability during a run time of at least 50 h of three Ni-catalysts obtained from two commercial supports and two preparation methods were used for comparison. An aluminum solution (9.40 g/L) obtained from an aluminum saline slag waste by acid extraction was used to synthesize the hexaaluminate by mixing with a stoichiometric amount of lanthanum nitrate and methanol/Peg400/PegMn400 under hydrothermal conditions at 493 K for 16 h. The Ni/LHA catalyst (10 wt% NiO) was obtained by impregnation of the synthesized support, calcined previously at 1473 K for 2 h. The resulting solids were characterized by several techniques as: X-ray diffraction (XRD), N₂ adsorption at 77 K, temperature-programmed reduction (TPR), scanning electron microscopy (SEM) and transmission electron microscopy (HR-TEM). In order to compare the catalytic behavior and properties of the Ni/LHA catalyst, three Ni catalysts obtained from two commercial supports (γ-Al₂O₃ and SiO₂) and two preparation methods (wet impregnation (I) and precipitation-deposition (PD)) were synthesized. Analysis of the TPR patterns for the catalysts allowed the type of metal support interaction and NiO species to be determined, with a weak interaction with the support being observed in Ni/LHA and Ni–I/SiO₂. The NiO species observed, with crystallite sizes between 9.7 and 40.4 nm, confirm the X-ray structural analyses. The Ni/LHA catalyst was found to be active and very stable in the DRM reaction after 50 h. The catalytic behavior was evaluated from the CO₂ and CH₄ conversions, as well as the H₂/CO selectivity, with values of 99% over almost all the time range evaluated. The behavior of this catalyst is comparable to that of Ni–I/Al₂O₃ and Ni-PD/SiO₂. The results found indicating that the strong interaction of nickel with the support favors the stability of the catalysts in the DRM reaction.     

六铝酸盐LaMnAl11O19-α催化合成甲基二氯化膦

采用共沉淀法制备了六铝酸盐 LaMnAl_(11)O_(19-α);以 LaMnAl_(11)O_(19-α)为催化剂、CH_4和 PCl_3为原料,合成甲基二氯化膦。考察了 n(CH_4):n(PCl_3)、催化剂粒径、反应温度对合成反应的影响,确定了较适宜的反应条件,并考察了催化剂的稳定性。实验结果表明,合成甲基二氯化膦的适宜反应条件为:以焙烧温度为1 200℃的 LaMnAl_(11)O_(19-α)为催化剂,n(CH_4):n(PCl_3)=10:1,催化剂粒径425～850μm,反应温度300℃。在此条件下,PCl_3的转化率为6.84%。使用LaMnAl_(11)O_(19-α)催化剂可降低反应温度,反应中不需通入氧气作为辅助催化剂,解决了高温通氧气易爆炸的问题,同时降低了生产成本,但LaMnAl_(11)O_(19-α)催化剂的稳定性较差,使用寿命短。     

氧化铝源对CA6多孔材料相组成和显微结构的影响

用Al(OH)₃、Al₂O₃微粉(uf-Al₂O₃)、工业Al₂O₃粉作为氧化铝源,CaCO₃为钙源,通过高温固相反应合成了六铝酸钙(CA₆)材料,研究了氧化铝原料对材料物相组成、显微结构和性能的影响。结果表明,以Al(OH)₃、Al₂O₃微粉、工业Al₂O₃为氧化铝源的试样在1 300 ℃时开始有CA₆相生成,各试样固相反应结束温度为1 500 ℃,继续提高烧成温度对物相组成没有影响。反应生成的CA₆显微形貌因氧化铝原料不同而不同,以Al(OH)₃为氧化铝源时,CA₆的显微形貌多为片状结构;以工业Al₂O₃为原料时,CA₆的显微形貌多为板片状和颗粒状;但以uf-Al₂O₃为氧化铝源时,CA₆的显微形貌则多为等轴状晶粒。以uf-Al₂O₃为氧化铝源时,制备的材料耐压强度和体积密度最高,气孔率最低;以Al(OH)₃为氧化铝源时,制备的材料耐压强度和体积密度最低,气孔率最高。