Ultrasound-assisted regeneration of zeolite/water adsorption pair

The use of ultrasound to enhance the regeneration of zeolite 13X for efficient utilization of thermal energy was investigated as a substitute to conventional heating methods. The effects of ultrasonic power and frequency on the desorption of water from zeolite 13X were analyzed to optimize the desorption efficiency. To determine and justify the effectiveness of incorporating ultrasound from an energy-savings point of view, an approach of constant overall input power of 20 or 25 W was adopted. To measure the extent of the effectiveness of using ultrasound, the ultrasonic-power-to-total power ratios of 0.2, 0.25, 0.4 and 0.5 were investigated and the results compared with those of no-ultrasound (heat only) at the same total power. To analyze the effect of ultrasonic frequency, identical experiments were performed at three nominal ultrasonic frequencies of ~28, 40 and 80 kHz. The experimental results showed that using ultrasound enhances the regeneration of zeolite 13X at all the aforementioned power ratios and frequencies without increasing the total input power. With regard to energy consumption, the highest energy-savings power ratio (0.25) resulted in a 24% reduction in required input energy and with an increase in ultrasonic power, i.e. an increase in acoustic-to-total power ratio, the effectiveness of applying ultrasound decreased drastically. At a power ratio of 0.2, the time required for regeneration was reduced by 23.8% compared to the heat-only process under the same experimental conditions. In terms of ultrasonic frequency, lower frequencies resulted in higher efficiency and energy savings, and it was concluded that the effect of ultrasonic radiation becomes more significant at lower ultrasonic frequencies. The observed inverse proportionality between the frequency and ultrasound-assisted desorption enhancement suggests that acoustic dissipation is not a significant mechanism to enhance mass transfer, but rather other mechanisms must be considered.     

无溶剂热处理固相转化法简易制备沸石咪唑酯骨架材料

设计开发了一种无需溶剂，通过热处理固相转化制备沸石咪唑酯骨架材料（ZIFs）的简易方法.该方法无需溶剂及其它预处理，只需将金属源与有机配体固相混合后于低温（200℃）热处理即可实现多孔晶体材料的制备.所合成材料H-ZIF-67为具有方纳石拓扑结构的纳米晶体，与传统方式合成的ZIFs材料一致.粉末X射线衍射（PXRD）分析结果表明产物的晶体结构与标准ZIFs谱图一致.通过扫描电子显微镜（SEM）、透射电子显微镜（TEM）、N₂吸附-脱附分析、热重分析（TGA）和傅里叶变换红外光谱（FTIR）等手段对合成的材料进行了表征，发现H-ZIF-67材料具有与ZIFs材料类似的特性.该方法经济、高效，摒弃了传统方法合成ZIFs材料周期长、处理过程复杂的弊端，为ZIFs材料的量产提供了新思路.     

Zeolite nanoparticles (H-ZSM5) as a highly efficient,green, and reusable heterogeneous catalyst for selective oxidation of sulfides to sulfoxides under mild conditions

H-ZSM5 is applied as an efficient, highly reusable, and heterogeneous catalyst for the oxidation of sulfides to sulfoxides using 30% H₂O₂ under solvent-free conditions at room temperature. A variety of aromatic and aliphatic sulfides with different functional groups were successfully oxidized with good to excellent yields in short reaction times. The catalyst can be easily recovered by simple filtration and recycled for several consecutive runs without any significant loss of its catalytic activity.     

Applications of Single-site Photocatalysts to the Design of Unique Surface Functional Materials

The isolated and tetrahedrally coordinated metal oxide (Ti, V, Cr, Mo and W-oxides) moieties can be included in the silica matrixes of silica-based microporous zeolite and mesoporous silica materials and named as “single-site photocatalysts”. Under UV-light irradiation these single-site photocatalysts form the charge transfer excited state, i.e., the excited electron–hole pair state which is located quite near to each other in different from the manner observed on semiconducting materials such as TiO₂, and play a significant role in various photocatalytic reactions. These single-site photocatalysts not only can promote photocatalytic reactions but also can be utilized to synthesis of functional materials. The nano-sized metal catalyst and visible-light sensitive binary oxide photocatalyst can be synthesized on the excited single-site photocatalyst under UV-light irradiation. The transparent mesoporous silica thin film with single-site photocatalyst generates the super-hydrophilic surface. In this review, our recent applications of single-site photocatalysts to synthesis of the surface functional materials have been introduced.     

Alkylation of 2-naphthol with long-chain olefins over zeolites

Alkylation of 2-naphthol with tripropylene in the presence of zeolite catalysts HBEA, H-Y and H-MFI was studied. Comparative studies on the catalytic properties of H-BEA, H-Y and H-MFI zeolites were carried out under identical reaction conditions. The results showed that the H-BEA catalyst exhibited outstanding catalytic performance; and the conversion and selectivity of 2-naphthol could be 52.1% and 86.3%, respectively. It was found that the structure and acid strength of zeolite catalysts were the major influencing factors for the conversion and selectivity of 2-naphthol alkylation.     

链状Silicalite-1分子筛的合成

在传统的合成体系中, 加入聚电解质聚二烯丙基二甲基胺盐酸盐(PDDA)自组装合成链状的Silicalite-1分子筛材料, 考察了PDDA的加入对产物的影响, 并对其进行了XRD和SEM表征.     

Ferric Single-Site Catalyst Confined in a Zeolite Framework for Propane Dehydrogenation

Non-oxidative dehydrogenation of propane is a highly efficient approach for industrial preparation of propene that is commonly catalyzed by noble Pt or toxic Cr catalysts and suffers from coking. In this work, ferric catalyst confined in a zeolite framework was synthesized by a hydrothermal procedure. The isolated Fe in the framework formed distorted tetrahedra, which were beneficial for the selective dehydrogenation of propane and reached over 95 % propene selectivity and over 99 % total olefins selectivity. This catalyst had a silanol-free structure and was oxygen tolerant, hydrothermally stable, and coke free, with a deactivation constant of 0.01 h⁻¹. This study provided guidance for the synthesis of structural heteroatomic zeolite and efficient propane non-oxidative dehydrogenation over early transition metals.     

凹凸棒土粘结剂对13X分子筛吸附性能的促进作用

以凹凸棒土为粘结剂制备了13X分子筛吸附剂.研究了其孔结构、表面电性和对水、CO2和N2分子的吸附性能,并与高岭土为粘结剂的同类吸附剂进行了比较.结果表明,凹凸棒土发达的孔隙结构、大的比表面和表面负电性质有利于其吸附容量的改善,而13X/凹凸棒土中丰富的中孔促进了其对CO2的吸附速率.另外由CO2吸附热力学分析可知,CO2在13X/凹凸棒土上具有较低的吸附热,结果将有利于其在吸附剂上的脱附.     

Cu-Bi纳米粉体的制备及其可见光光催化性能研究

以Cu（NO3）2、Bi（NO3）3、COfNH）2为原料,聚乙二醇（PEG）为分散剂,采用均匀共沉淀法制备了Cu-Bi催化剂,用X-射线粉末衍射法、能量色散法、透射电镜和紫外－可见漫反射光谱法对催化剂的组成、粒径大小、表面形貌和光学吸收性能进行了详细表征,并以酸性大红和亚甲基蓝为目标降解物,考察了所制备的Cu－Bi催化剂在可见光下的光催化性能。实验结果表明,该催化剂为类球形纳米粉体,粒度均匀,粒径约50nm。在可见光作用下,该催化剂对酸性大红和亚甲基蓝均表现出良好的光催化性能,且在240min前,对酸性大红的降解率要优于亚甲基蓝;240min后则两者的降解效果相近。     

Dehydration performance of a hydrophobic DD3R zeolite membrane

The all silica DDR membrane turns out to be well suited to separate water from organic solvents under pervaporation conditions, despite its hydrophobic character. All-silica zeolites are chemically and hydrothermally more stable than aluminum containing ones and are therefore preferred for membrane applications, including for dehydration, even though these type of membranes are hydrophobic. Permeation of water, ethanol and methanol through an all-silica DDR membrane has been measured at temperatures ranging from 344 to 398 K. The hydrophobic membrane shows high water fluxes (up to 20 kg m⁻² h⁻¹). The pure water permeance is insensitive to temperature and is well described assuming weak adsorption. Excellent performance in dewatering ethanol (N=2$N=2$ kg m⁻² h⁻¹and _αw=1500${\alpha }_{\text{w}}=1500$ at 373 K and _xw=0.18$x_{\text{w}}=0.18$) is observed and the membrane is also able to selectively remove water from methanol (N=5$N=5$ kg m⁻² h⁻¹ and _αw=9${\alpha }_{\text{w}}=9$). Water could also be removed from methanol/ethanol/water (_αwater_/EtOH=1500${\alpha }_{\text{water}/\text{EtOH}}=1500$, _αMeOH_/EtOH=70${\alpha }_{\text{MeOH}/\text{EtOH}}=70$ at 373 K) mixtures, even at water feed concentrations below 1.5 mol%.