Bingchun Wang

Effect of water on the ionothermal synthesis of molecular sieves

AlPO4-11 and AlPO4-5 molecular sieves are ionothermally prepared without addition of water by using anhydrous starting materials, such as NH4H2PO4, pseudoboehmite (AlOOH), and NH4F. The synthesis appears to be an autocatalytic process. Water has a remarkable effect on the synthesis process. Addition of reagent quantities of water (H2O/Al = 1, molar ratio) can enhance the crystallization kinetics greatly.

One‐Step Hydrotreatment of Vegetable Oil to Produce High Quality Diesel‐Range Alkanes

A one-step hydrotreatment of vegetable oil combining deoxygenation and isomerization to directly produce low cloud point, high quality diesel is devised. The Pt/zeolite bifunctional catalysts prepared by using SAPO-11 and ZSM-22 zeolites as supports are used in this process. Catalytic reactions are conducted in a fixed-bed reactor under a hydrogen atmosphere. Over the bifunctional catalyst, 100 % conversion of soybean oil is obtained at 357 °C, 4 MPa, and 1 h(-1), and 80 % organic liquid yield is achieved, which is close to the maximum theoretical liquid yield. In the organic products, the alkanes selectivity is 100 % with an i-alkanes selectivity above 63 %. NH(3)-temperature programmed desorption (TPD), pyridine IR spectroscopy, and other characterization techniques are used to study the effect of the support acidity on the reaction pathway. Over the Pt/zeolite bifunctional catalyst with less strong Lewis acid sites, the reaction proceeds via the decarboxylation plus decarbonylation pathway. This one-step method provides a new strategy to produce low cloud point, high quality diesel from biomass feedstock in a more economic and attractive way.

Ionothermal Synthesis of an Aluminophosphate Molecular Sieve with 20‐Ring Pore Openings

Crystalline porous materials with large or extralarge pores continue to be of particular significance in both industry and academia for their potential applications in shape-selective catalysis and adsorption/separation. Of these zeolitic materials, especially aluminosilicateand aluminophosphate-based molecular sieves are of prime interest because of their high stability associated with their widespread use in many established process and emerging applications. The materials VPI-5 (VFI framework type, 18-ring) and UTD-1 (DON framework type, 14-ring) were the first extra-large pore (pores constructed of more than 12 Tatoms) aluminophosphate and aluminosilicate materials discovered. The oxide frameworks are built up by corner-sharing [AlO4] and [PO4] tetrahedra as well as [AlO4] and [SiO4] tetrahedra. In the search for materials with even larger pores, an anionic open-framework aluminophosphate JDF-20 (20-ring) was reported; however, it could not be classified as a zeolite because its framework (with an Al/P ratio of 5:6) is unstable upon removal of the occluded protonated templates by calcination. Larger pore openings were also achieved using Ge or Ga as the framework Tatom in a high amount, for example in ECR-34 (ETR framework type, 18-ring), ITQ-33 (18-ring), cloverite (-CLO framework type, 20ring), and ITQ-37 (30-ring). In this context, the use of Ge or Ga as framework atoms as well as fluoride has been found to facilitate the formation of a double four-ring (D4R) unit. This is in agreement with the prediction by Brunner and Meier that structures with extra-large pores should contain a large number of threeand four-membered rings. Ionothermal synthesis, in which ionic liquids act as both the solvent and template, is a novel method that has attracted great interest in the synthesis of zeolitic and other porous materials. Besides the advantage of experimenting at ambient pressure, ionic liquids offer different chemistry and structural variety associated with the use of additional amines as structure-directing agents (SDA), and therefore open up new vistas for the synthesis of new porous materials. Herein, we report the ionothermal synthesis of the first aluminophosphate molecular sieve with 20-ring pore openings, denoted as DNL-1 (Dalian National Laboratory Number 1). This molecular sieve was confirmed as a structural analogue to the gallophosphate molecular sieve cloverite by using a combination of Rietveld refinement of powder X-ray diffraction (PXRD) data and NMR analysis. Moreover, in comparison to cloverite, DNL-1, as-synthesized and calcined, exhibits excellent stability. DNL-1 was synthesized in the ionic liquid 1-ethyl-3methylimidazolate bromide ([emim]Br) with 1,6-hexanediamine (HDA) as the co-SDA. The detailed synthetic procedure is described in the Experimental Section. The assynthesized DNL-1 material displays uniformly globular agglomerates of grainlike nanocrystals with a diameter of about 20 mm (see the Supporting Information). Analysis by energy dispersive X-ray spectroscopy (EDX) indicates the P/ Al/F molar ratio of approximately 3:3:1. The inductively coupled plasma (ICP) analysis gives the content (wt%) of Al 16.50 and P 16.65. The elemental and thermogravimetric (TG) analyses show the content (wt%) of C 9.72, N 3.64, H 3.29, and a total weight loss of 34%. Combined with the results of the structure refinement (see below), the chemical formula of DNL-1 was determined as j (C6N2H18)104(C6N2H11)80(H2O)910 j [Al768P768O2976(OH)192F288]. Using the initial structure model from cloverite, the Rietveld refinement of as-synthesized DNL-1 was successfully performed in space group Fm 3c with refined unit cell parameter a= 51.363(1) , which is comparable to that of cloverite a= 51.713 , considering the smaller ionic radius of Al. Similar results were observed in the all-silica and Gecontaining polymorph C of zeolite Beta. Figure 1 shows the very good agreement between observed and calculated PXRDpatterns, taking into account the limited signal to noise ratio, in particular for the data collected at a high angle which can be reflected from the expected R factor of 14.5%. These results adequately confirm that DNL-1 is a pure aluminophosphate analogue of the -CLO structure. The skeletal model of the refined framework structure is shown in Figure 2. The framework of DNL-1 shows the general features of the -CLO structure: 1) two nonintersecting three-dimensional channel systems with 20-ring and 8-ring windows, respectively, 2) four terminal hydroxy groups (Al [*] Y. Wei, Prof. Z. Tian, R. Xu, Dr. H. Ma, R. Pei, Prof. W. Zhang, Prof. Y. Xu, Dr. L. Wang, K. Li, Dr. B. Wang, G. Wen, Prof. L. Lin State Key Laboratory of Catalysis Dalian National Laboratory for Clean Energy Dalian Institute of Chemical Physics Chinese Academy of Sciences, Dalian 116023 (China) Fax: (+86)411-843-79151 E-mail: tianz@dicp.ac.cn

Ionothermal Synthesis of Magnesium‐Containing Aluminophosphate Molecular Sieves and their Catalytic Performance

Owing to their promising catalytic and adsorptive properties, microporous materials, often referred to as molecular sieves or open-framework materials, have attracted more and more attention in different research fields. Among them, microporous aluminiophosphate molecular sieves (designated AlPO4-n) have been extensively studied by many authors, owing to their wonderfully complex structures and broadly applications since their discovery in 1982. However, because the frameworks of these materials are neutral and lack of Bronsted acid sites, sometimes they can not be used in catalysis directly. Nevertheless, the lattice Al and/or P atoms in the AlPO4-n frameworks can be partially replaced by silicon (designated (SAPO-n) and/or other metal elements (designated MeAPO-n), to form frameworks with Bronsted acid sites and/or catalytically active metal centers. Commonly, AlPO4-n and MeAPO-n compounds are often crystallized from a gel under hydrothermal or solvothermal conditions. Recently, a novel synthetic route (ionothermal synthesis) provides a potential route to making these microporous materials. Ionothermal synthesis is the use of an ionic liquid or eutectic mixture as the reaction solvent and if necessary, the structure-directing agent in the synthesis of materials. Ionic liquids are special molten salts typically containing organic cations and inorganic anions. The peculiar properties of ionic liquids endow the ionothermal synthesis many interesting features and potential advantages over the traditional methods of molecular sieve synthesis. For example, the ionothermal synthesis can take place at ambient pressure because of the vanishingly small vapor pressure of ionic liquids, which eliminates the safety concerns associated with high pressures. In addition, the excellent microwave-absorbing property of ionic liquids allows the ionothermal synthesis being carried out under microwave conditions, leading to the rapid crystal-growth rate and high product selectivity. Although many AlPO4-based molecular sieves including some novel-framework topologies have been prepared using ionothermal method, the amount of the MeAPO-n structures synthesized ionothermally is relatively small. To date, only several SAPO-n and CoAPO-n 15] structures could be obtained by using this new synthetic technique. Moreover, the research on the applications of these MeAPO-n compounds to catalysis or gas adsorption has not been reported in the literature. Herein we demonstrate that the ionothermal synthesis method can be applied to the synthesis of MeAPO-n materials with excellent catalytic performance. In the present work, a magnesium compound was introduced into the reaction system of AlPO4-n and several Mg-containing aluminophosphate molecular sieves were successfully synthesized in 1-butyl 3-methylimidazolium bromide ionic liquid ([bmim]Br). Results are presented about the physical and chemical characterization (such as X-ray diffraction: XRD, X-ray fluorescence: XRF, scanning electron microscopy: SEM, Brunauer–Emmett–Teller: BET, NH3-temperature programmed desorption: NH3-TPD, thermogravimetric: TG, and NMR analysis) of the MAPO samples obtained with different Mg contents and amine as well as their catalytic evaluation in the hydroisomerization of n-docecane. Table 1 summarizes the details of the synthesis conditions and the products obtained ionothermally. Only the AlPO4tridymite dense phase could be obtained at 170 8C for 3 day without the addition of metal elements (Table 1, AlPO). [a] Dr. L. Wang, Dr. Y.-P. Xu, B.-C. Wang, Prof. Z.-J. Tian, Prof. L.-W. Lin Dalian National Laboratory for Clean Energy State Key Laboratory of Catalysis Dalian Institute of Chemical Physics, Chinese Academy of Sciences 457 Zhongshan Road, Dalian, 116023 (China) Fax: (+86)411-84379151 E-mail : wl7830@dicp.ac.cn tianz@dicp.ac.cn [b] Prof. S.-J. Wang, Prof. J.-Y. Yu Department of Chemical Engineering Dalian Institute of Light Industry Dalian, 116034 (China) Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/chem.200801383.

Ionothermal Synthesis of Aluminophosphate Molecular Sieve Membranes through Substrate Surface Conversion

Applications of zeolite membranes in separation, chemical sensors, and catalytic membrane reactors have led to extensive studies on their fabrication. To date, mainly silicatebased zeolite membranes of the structure types MFI, DDR, LTA, and FAU have been synthesized on different substrates and evaluated for singleor multiple-gas permeation. Routes for the synthesis of zeolite membranes can be broadly classified into two categories: in situ and secondary growth synthesis, both of which are derived from the strategy of hydrothermal zeolite synthesis. However, the high autogenous pressure associated with hydrothermal procedures is inconvenient for preparation of zeolite membranes, especially for large-scale production, due to safety concerns and the risk of molecular sieve collapse. On the other hand, although aluminophosphate and silicoaluminophosphate membranes for gas separation have been prepared, there are few reports on the preparation of aluminophosphate molecular sieve membranes, which suggests that hydrothermal preparation of such membranes may be difficult. Ionothermal synthesis, which uses ionic liquids as reaction media instead of water or organic solvents, allowed highly efficient preparation of aluminophosphate molecular sieves under ambient pressure. Ionic liquids (ILs) are commonly defined as salts that consist of organic cations and inorganic anions with melting temperatures below 100 8C. ILs are well known as environmentally benign and designable solvents, which endow ionothermal synthesis with interesting features and many potential advantages over the hydrothermal method. As a result of the negligible vapor pressure of ILs, ionothermal synthesis can take place at ambient pressure, which eliminates safety concerns. The organic cation of the IL can act as a structure-directing agent (SDA), or play a cooperative structure-directing role together with introduced amines and quaternary ammonium compounds. AEL, AFI, CHA, LTA, and CLO types of aluminophosphate molecular sieves have been successfully synthesized by ionothermal methods. Ionothermal synthesis is a promising method for the preparation of aluminophosphate molecular sieve membranes under ambient pressure. Yan and co-workers prepared AlPO-11 and SAPO-11 films on aluminum alloys as anticorrosion coatings by in situ ionothermal synthesis. To the best of our knowledge, no permeable membrane has been previously prepared on a porous substrate by the ionothermal method. Here we report an ionothermal method for the synthesis of permeable aluminophosphate molecular sieve membranes on porous alumina disks by substrate-surface conversion. Molecular sieve membranes of types AEL, AFI, CHA, and LTA were prepared by placing homemade d-alumina substrates (2.0 mm thickness, 20 mm diameter, and 10 nm average pore size; see Supporting Information for details) in a solution of IL, phosphoric acid, hydrofluoric acid, and, if required, organic amines with no additional source of Al. Table 1 lists the initial solution composition, crystallization

Basicities and transesterification activities of Zn–Al hydrotalcites-derived solid bases

Solid bases were prepared by calcining as-prepared Zn–Al hydrotalcites at different temperatures. The evolutions of their structure and basicity were characterised using X-ray diffraction, thermogravimetric analysis, infrared spectroscopy of CO2 adsorption and temperature programmed desorption of methanol. With an increase in the calcination temperature, the as-prepared Zn–Al hydrotalcites were firstly converted into dehydrated Zn–Al hydrotalcites and next converted into Zn–Al oxides. The basic sites of these solid bases changed from OH groups to Mn+–O2− (M = Zn or Al) pairs and isolated O2− ions. These solid bases were evaluated in transesterification reactions used for biodiesel production. The dehydrated Zn–Al hydrotalcites obtained at 473 K exhibit the highest activity, with a biodiesel yield of approximately 76% at 413 K, 1.7 MPa and 1.0 h−1. This catalyst exhibits no deactivation after about 150 h. The structure–reactivity relationship of the catalyst is also discussed.

Ionothermal synthesis of aluminophosphate molecular sieves

Effects of ionic liquid structures on the aluminophosphate molecular sieve products in ionothermal synthesis process were investigated. The results showed that the possible structure-directing effect of ionic liquid might exist during ionothermal synthesis. Microwave heating was introduced into the ionothermal synthesis, which led to a fast and safe process for preparation of molecular sieves. The ionothermal synthesis of AEL type magnesium aluminophosphate molecular sieve (MgAPO-11) was also investigated in the experiments.