Preparation of High-purity Alumina via Hydrolysis of Aluminum Isopropoxide after Desilication with Lanthanum Oxide

High-purity alumina refers to ultra-fine alumina powder with a purity exceeding 99.99% and a uniform particle size. This material exhibits excellent corrosion resistance, high-temperature resistance, wear resistance, and oxidation resistance. Owing to the high silicon content of alumina prepared by means of the alcohol-aluminum hydrolysis method, the purity of the alumina is often unsatisfactory. Therefore, in this work, a new method for adding lanthanum oxide to isopropanol in the early aluminum isopropoxide synthesis stage is proposed. When lanthanum oxide was added, the silicon content of the precursor aluminum isopropoxide decreased to 0.0051%.Remove calcium, sodium, magnesium and other impurities by cleaning with hydrochloric acid under an ultrasonic field. The optimal hydrolysis conditions were determined as follows: hydrolysis temperature: 55, hydrolysate concentration: 80%, water to alkoxide ratio: 6:1. The alumina precursor calcined at 1200 yielded a high-purity alumina with a purity level of more than 99.99%, and the particle size reaches 2.037 μm.

MOR/DEA/TEA mixed-template synthesis of CHA-type SAPO with different silica and alumina sources

We investigated the effects of different sources of alumina (Pseudo-boehmite, Aluminum hydroxide, Aluminum tri-sec-butylate, Aluminum isopropoxide, and Aluminum phosphate) and silica (Silica sol, Silicic acid, Tetraethyl orthosilicate, and sodium silicate)...

Rapid synthesis of hierarchical SSZ-13 zeolite microspheres via a fluoride-assisted in situ growth route using aluminum isopropoxide as aluminum source

Hierarchical SSZ-13 were quickly synthesized by adding a small quantity of hydrofluoric acid in the starting gel using aluminum isopropoxide as aluminum source.

Surfactant-Assisted Fabrication of Alumina-Doped Amorphous Silica Nanofiltration Membranes with Enhanced Water Purification Performances

Surfactant-templated 5 mol% Al2O3-doped silica membranes nanofiltration membranes were synthesized via the sol-gel method, and afterward, were optimized, and tested with respect to the permeability and rejection rate. The disordered silica network was stabilized by doping 5 mol% alumina. Tetraethyl orthosilicate and aluminum isopropoxide were used as the silica and alumina precursors, respectively. Cetyltrimethylammonium bromide (CTAB) was used not only as a pore-forming agent, but also to control the reaction rate of the aluminum isopropoxide, thus obtaining highly homogeneous materials. The results about filtration of model solutions showed that the optimized membranes are featured by both a relatively high water permeability (1.1–2.3 L·m−2·h−1 ·bar−1) and a high rejection for salts (74% for NaCl, and >95% for MgSO4 and Na2SO4) and organic pollutants (e.g., about 98% for caffeine). High rejection of divalent ions and organic molecules was also observed when a real wastewater effluent was filtered. The influence of the synthesis conditions on the membrane performance is discussed.

Effect of Configuration of a Bulky Aluminum Initiator on the Structure of Copolymers of L,L-Lactide with Symmetric Comonomer Trimethylene Carbonate

The effect of configuration of an asymmetric bulky initiator 2,2’-[1,1’-binaphtyl-2,2’-diyl- bis-(nitrylomethilidyne)]diphenoxy aluminum isopropoxide (Ini) on structure of copolymer of asymmetric monomer L,L-lactide (Lac) with symmetric comonomer trimethylene carbonate (Tmc) was studied using polarimetry, dilatometry, SEC and 13C NMR. When the S-enantiomer of Ini was used the distribution in copolymer chains at the beginning of polymerization is statistical, with alternacy tendency, changing next through a gradient region to homoblocks of Tmc. When, however, R-Ini was used, the product formed was a gradient oligoblock one, with Tmc blocks prevailing at the beginning, changing to Lac blocks dominating at end part of chains. Initiation of copolymerization with the mixture of both initiator enantiomers (S:R = 6:94) gave multiblock copolymer, of similar features but shorter blocks. Analysis of copolymerization progress required complex analysis of dilatometric data, assuming different molar volume contraction coefficients for units located in different triads. Comonomer reactivity ratios of studied copolymerizations were determined.

Effect of Configuration of a Bulky Aluminum Initiator on the Structure of Copolymers of L,L-Lactide with Symmetric Comonomer Trimethylene Carbonate

The effect of configuration of an asymmetric bulky initiator 2,2’-[1,1’-binaphtyl-2,2’-diyl- bis-(nitrylomethilidyne)]diphenoxy aluminum isopropoxide (Ini) on structure of copolymer of asymmetric monomer L,L-lactide (Lac) with symmetric comonomer trimethylene carbonate (Tmc) was studied using polarimetry, dilatometry, SEC and 13C NMR. When the S-enantiomer of Ini was used the distribution in copolymer chains at the beginning of polymerization is statistical, with alternacy tendency, changing next through a gradient region to homoblocks of Tmc. When, however, R-Ini was used, the product formed was a gradient oligoblock one, with Tmc blocks prevailing at the beginning, changing to Lac blocks dominating at end part of chains. Initiation of copolymerization with the mixture of both initiator enantiomers (S:R = 6:94) gave multiblock copolymer, of similar features but shorter blocks. Analysis of copolymerization progress required complex analysis of dilatometric data, assuming different contraction coefficients for units located in different triads. Comonomer reactivity ratios of studied copolymerizations were determined.