Synthesis, Characterization of Mesoporous Al-Mg Composite Oxide and Catalytic Performance for Oxyethylation of Fatty Alcohol

A mesoporous Al-Mg composite oxide with a hexagonal structure was synthesized with aluminium nitrate and magnesium nitrate as the reagents and sodium dodecyl sulfate（SDS） as the template in the presence of ethylenediamine. The XRD, nitrogen adsorption-desorption and TEM studies indicate that the composite has a hexagonal framework structure and an average pore diameter of 2. 6 nm. The TG/DTA spectra indicate that the decomposition and the removal of the occluded surfactant of the sample take place in a range of 230-550 ℃. The mesoporous Al-Mg composite oxide exhibites a highly catalytic activity for the oxyethylation of fatty alcohols. Narrow-range distributed ethoxylates are formed in the presence of the mesoporous Al-Mg composite oxide catalyst. The distribution selectivity coefficient（Cx） is 24 when the mesoporous Al-Mg composite oxide was used as a catalyst for the oxyethylation of octanol and the average adduct degree of ethoxylates is 6. 4.

Oxidation of Al_2O_3-30%TiCN-0.2%Y_2O_3 Composite

The oxidation behavior of Al2O3-30%TiCN-0.2%Y2O3 composite and its effect on high temperature bending strength was studied. The result indicates that the mass gain during static oxidation of the material under normal atmosphere follows the parabolic law. Oxide increases with increasing temperature and prolonging time. It has good oxidation resistance. The product of oxidation of the material is TiO2. Therefore, the volume of the material expands. The oxide film is destroyed because residual stress inside the oxide film is released. Proper oxidation is beneficial to the improvement of bending strength of Al2O3-30%TiCN-0.2%Y2O3 composite. The strength increase is up to 4.5%.

Preparation of SiC_p/Al_2O_3-Al Composites by Directed Metal Oxidation

SiCp/Al2O3-Al composites were synthesized by means of direct metal oxidation method. The composition and microstructures of the composites were investigated using X-ray diffraction （XRD）, scanning electron microscopy （SEM） and metallurgical microscope. The effects of technical parameters on the properties of the product were analyzed. The results indicate that the composite possesses a dense microstructure, composed of three interpenetrated phases. Of them, SiO2 layer prohibits the powdering of the composites; Mg promotes the wetting and infiltration of the system and Si restricts the interfacial reaction while improving the wetting ability between reinforcement and matrix.

用于菜籽油酯交换过程的Mg-Al复合氧化物催化剂

以共沉淀法制备了Mg -Al复合氧化物催化剂 ,XRD表征结果表明 ,沉淀所得催化剂前体晶相均一 ,为层状Mg6 Al2 (OH) 1 6 CO3·4H2 O水滑石结构。经 5 0 0℃煅烧后得到具有良好酯交换活性的Mg -Al复合氧化物催化剂 ,在常压、(65± 1)℃、4h、醇 /油摩尔比为 6、催化剂加入量 (催化剂质量 /油质量 )为 1 5 %的条件下 ,菜籽油 -甲醇酯交换反应甲酯收率达到 90 %。CO2 -TPD实验表明 ,制备的催化剂比MgO具有更强和更多的碱性位 ,其催化性能与所拥有的碱中心性质直接相关 。

Mg-Al-Zr金属复合氧化物除氟影响因素

采用共沉淀-煅烧法制备Mg-Al-Zr金属复合物,并用扫描电镜和X射线衍射对其进行表征,考察了吸附剂质量浓度、吸附时间、pH、初始氟质量浓度和共存阴离子对除氟影响。结果表明,在初始溶液pH=4~10,吸附剂质量浓度为3 g/L,氟初始质量浓度为40 mg/L时,对溶液中的氟去除效果最佳,吸附平衡时间为300 min。等温吸附数据分析显示其等温吸附特征可用Langmuir等温吸附方程描述,由其计算饱和吸附量为48.90 mg/g。共存阴离子对吸附材料除氟效率影响力大小为:PO_4^(2-)>CO_3^(2-)>SO_4^(2-)>NO_3^-。吸附剂再生循环3次后,除氟效率仍在70%以上。

镁在Al_2O_3/Al-Mg-Si复合材料中的作用(英文)

研究了镁对Al-Mg-Si合金熔体氧化热力学与动力学的作用,以及对Al2O3/Al-Mg-Si复合材料组织与性能的作用。热力学与动力学分析表明:镁促进了Al2O3的形核和长大,Al2O3/Al复合材料的性能改善是由于尖金石(MgAl2O4)的分解所导致的组织细化。但在合金中,镁含量太高或太低都对Al2O3的形核和长大不利。

焙烧温度对Ru/Ba-Mg(Al)O_4氨合成催化剂性能影响

采用超声-沉淀-强静电吸附法制备了化学性质比较稳定的掺钡纳米镁铝复合氧化物Ba-Mg(Al)O4,并以其为载体、Ru3(CO)12为活性组分前驱体,制备了一系列钌基氨合成催化剂。通过场发射扫描电镜、X射线衍射和N2物理吸附等表征手段,重点考察了焙烧温度对载体的物相组成和表面织构的影响。结果表明,随着焙烧温度的升高,制备的载体比表面积逐渐下降,表面碱性增强。当载体焙烧温度为780℃时,制备的负载型Ru/Ba-Mg(Al)O4催化剂表现出较高的催化活性,在425℃、10 MPa和10 000 h-1条件下,出口氨浓度达到49.17 mmol.(g.h)-1。

阳极氧化法制备Mg-Al复合氧化物绝缘层的研究

栅绝缘层是薄膜晶体管(TFT)的关键组成部分,低成本及低温制备是其未来的发展方向。阳极氧化法是可以实现这些目的的制备工艺技术之一。本文首先采用电子束蒸发在150℃的玻璃基板上制备Mg-Al合金薄膜,然后使用阳极氧化法形成Mg-Al复合氧化物薄膜,并对不同制备工艺条件下的薄膜结构、绝缘性能等进行了初步研究。所获得的Mg-Al氧化物薄膜具有均匀的非晶态结构以及较好的绝缘性能,适合于用作TFT的栅绝缘层。

Mg-Fe-Al复合氧化物的制备及其对二甲酚橙吸附性能研究

通过化学共沉淀法成功制备了Mg-Fe-Al复合氧化物,运用扫描电子显微镜(SEM)、红外光谱(FT-IR)、X射线衍射仪和比表面积(BET)等手段详细表征了Mg-Fe-Al复合氧化物的结构和形貌,并研究了Mg-Fe-Al复合氧化物对二甲酚橙的吸附行为。实验结果表明,当Mg-Fe-Al的摩尔比为2∶1∶1,合成pH为8,煅烧温度为300℃时,得到的Mg-Fe-Al复合氧化物比表面积达到316.54m^2·g^(-1),对二甲酚橙的最大吸附量达573.86mg·g^(-1)。该吸附过程符合Langmuir吸附方程,属于单分子层吸附。动力学研究表明,该吸附过程符合准二级动力学模型,吸附4h后达到平衡状态。

Mg/Al氧化物催化高酸原油酯化降酸的研究

系统地研究了Mg/Al氧化物作为酯化降酸催化剂的性能。实验证明镁铝氧化物具有催化高酸原油酯化反应的能力,以蓬莱19-3高酸原油为原料,当催化剂加入量(ω)为1%、醇酸摩尔比为3:1、反应温度为250℃、反应时间为1h时,酯化反应降酸率达90.5%,催化剂多次重复使用后催化活性没有下降。经分析,催化剂表面碱性强度的改变是催化活性改变的原因,随着碱性增强,降酸率增加。蓬莱19-3原油经酯化降酸后,原油酸值降至0.5mgKOH/g以下,经实沸点蒸馏后,各馏分油酸值比酯化前大幅下降。

Mechanism of pore formation and structural characterization for mesoporous Mg-Al composite oxides

Mg-Al layered double hydroxides (LDH) with different particle sizes were prepared using different aging times at high supersaturation by a new method developed in our laboratory. The key features of this method are a very rapid mixing and nucleation process followed by a separate aging process. By calcination of LDH at 500°C, mesoporous Mg-Al composite oxides with an extremely narrow pore size distribution were produced. The crystal structure of the Mg-Al composite oxides was a multiphasic one consisting of MgO-like crystals and a layered material.

复合变质对不同镁量原位Mg_2Si/Al复合材料组织的影响

在不同镁含量铸造Mg2Si/A1-Si复合材料过程中,加入混合稀土氧化物与CaCO3作为变质剂,并采用光学显微镜研究了复合变质对组织的影响。结果表明,变质剂加入量与镁的加入量有关。0.2%的混合稀土氧化物与0.3%的CaCO3使Al-10%Mg-20%Si的初生Mg2Si尺寸由原来的75μm减小到25μm左右,变质效果显著,并初步探讨了其变质机理。

PEO processing of AZ91Nd/Al_(2)O_(3) MMC-the role of alumina fibers

This work reports the influence of alumina fiber reinforcement of an AZ91Nd MMC(metal matrix composite)on the PEO coating formation process in a sodium phosphate-based electrolyte.By comparison with the pure AZ91Nd,the evolution of alumina fiber during the processing and the characteristics of the resultant PEO coating were investigated.The voltage response as a function of processing time was changed.Lower voltage in the presence of alumina fiber is responsible for the lower coating thickness.The morphology and phase composition of the coatings are also influenced by the incorporation of the fiber.Firstly,the fiber is embedded in the coating and interrupts the continuity of the coating.With increasing processing time,the fiber is found to be reactively incorporated in the coating.The intention to produce a MgAl_(2)O_(4)containing coating is achieved and it is mainly accumulated near the coating surface.However,due to the low number of fibers,the Al content is overall still low and only near to the fibers the MgAl_(2)O_(4)spinel phase can form.

Al_2O_3/Al 复合材料氧化生长的动力学研究

通过热重分析实验，研究了Ａｌ－Ｍｇ－Ｓｉ合金熔体在高温空气气氛中直接氧化的孕育期与工艺温度及母合金中Ｍｇ、Ｓｉ含量的关系，摸清了铝合金本体氧化的表观活化能与母合金Ｍｇ、Ｓｉ含量的关系。

DIMOX工艺制备复合材料熔体表面Mg蒸气扩散动力学研究

从热力学角度分析了 Al-Mg-Si合金直接氧化生长 Al2 O3/Al复合材料工艺过程中 ,熔体表面 Mg蒸气层的存在 ,按照气体扩散传质动力学原理 ,解析了 Mg蒸气层的厚度。结果表明 :熔体上方 Mg蒸气层的厚度δ与熔体表面距坩埚上沿的距离 L成正比 ,坩埚上沿处 O2的摩尔分数增加 ,Mg蒸气层厚度减小。 Mg蒸气层厚度与材料自氧化生长速度密切相关。

直接氧化法制备Al_2O_3／A1复合材料氧化生长动力学研究

系统分析了Ｍｇ含量、Ｓｉ含量、高温保温湿度和高温保温时间对直接氧化法制备Ａｌ２０３／Ａ１复合材料氧化生长物重量及其中Ａｌ２Ｏ３；百分含量的影响规律，确定了上述工艺参数的最佳取值范围，并从理论上深入分析了所得影响规律的成因①．

Interfacial reaction between the oxidized SiC particles and Al-Mg alloys

The interfacial reactions of oxidized SiC particles reinforced Al-Mg matrix composites were investigated by the field emission-scanning electron microscopy (FE-SEM), TEM and X-ray diffraction. It was found that the nanoscale MgO forms initially due to the interfacial reaction, then whether it reacts with molten Al continuously or not depends on the content of Mg in the matrix and its covering densification at the surface of particles. When there is not enough Mg in the matrix for the formation of dense MgO layer, MgO will transform into MgAl2O4 crystal owing to the continuous reaction with SiO2 and molten Al. When dense MgO layer forms at the surface of the particles due to the affluence of Mg for the initial reaction, it will protect the inner SiC from the attack of molten Al. However, the reaction products of both MgO and MgAl2O4 are thermo-stable phases at the surface of the particles under high temperature. The results clarify the interfacial reaction route and they are of great value to the

镁铝复合氧化物负载醋酸钾催化大豆油酯交换反应制备生物柴油

在镁铝复合氧化物上通过等体积浸渍法负载醋酸钾,煅烧后获得的碳酸钾均匀分布在镁铝氧化物体系中,二者发生的强相互作用使催化剂表面形成大量的强碱中心。随着醋酸钾负载量的增加,大豆油和甲醇的酯交换反应活性升高,当负载量超过20%时,反应4 h后生物柴油产率在80%以上,反应负载中碳酸钾会从镁铝氧化物表面流失。

水滑石的合成及其对催化丙酮合成异佛尔酮的影响

用共沉淀法合成镁铝水滑石,焙烧制得镁铝复合氧化物催化剂.采用连续微反装置,以丙酮缩合生成异佛尔酮为探针反应,探讨了镁铝水滑石的合成对镁铝复合氧化物催化性能的影响,采用XRD、TG-DTA等分析手段对催化剂前体镁铝水滑石进行表征.结果表明,镁铝水滑石的合成工艺对水滑石的微观晶体结构有较大影响,镁铝比是较为重要的影响因素,在镁铝比为1∶1时水滑石结晶度较好,晶形完整.活性评价结果表明,适宜的合成参数为:镁铝比为1∶1,金属离子总浓度为0.2 mol.L-1,沉淀剂用量为1.5倍.对优化合成工艺条件下制备的催化剂进行热重分析,结果显示:焙烧温度超过500℃时,水滑石的层状结构将被完全破坏,记忆效应将不再起作用,热稳定性大大提高.与活性评价结果关联,确定镁铝水滑石的适宜焙烧温度为550℃.丙酮在此条件下合成的催化剂上转化率为19.74%,异佛尔酮选择性为55.91%.

钙镁铝复合金属氧化物催化微藻油脂制备生物柴油

采用共沉淀法制备钙镁铝类水滑石化合物,并以其作为前驱体,再经高温煅烧后制得钙镁铝复合金属氧化物催化剂,并考察了煅烧温度、碱度、碱土金属含量、醇油比和反应温度对生物柴油转化率的影响。当催化剂煅烧温度为400℃,钙镁铝物质的量比为1.5∶4.5∶2,醇油物质的量比为14∶1,催化剂质量分数4.5%,反应温度为65℃,反应时间5h时,转化率达到最高93%。因此,这类具有高活性的催化剂在制备生物柴油中有良好的应用前景。