The Form of Sulfate in Pseudo-Boehmite and Its Effect on Properties of Pseudo-Boehmite

A series of pseudo-boehmite samples with their sulfate radicals(SO2-4) concentration ranging from 0.9% to 3.0% were prepared by the reaction of Na Al O2 solution on Al2(SO4)3 solution. The existing form of sulfate radicals was investigated. Results have shown that sulfates in pseudo-boehmite included two parts, the soluble sulfate radicals and the insoluble sulfate radicals, which accounted for 99% of the total amount of sulfate radicals. XRD, low-temperature N2-adsorption, and TEM were used to characterize the properties of these pseudo-boehmite samples. Results have shown that the relative crystallinity and crystal size of pseudo-boehmite decreased with the increase of sulfate radicals in the support. In the meanwhile, the bound water content in pseudo-boehmite increased. The TEM images of pseudo-boehmite indicated that the pseudoboehmite was prone to become amorphous hydrated alumina. However, the effect of sulfate content on the specific surface area and pore structure of aluminium oxide was insignificant.

YAG∶Ce Phosphors for WLED via Nano-Pesudoboehmite Sol-Gel Route

The sub-micron sized YAG ： Ce phosphors were synthesized via a modified sol-gel method by peptizing nano-pesudoboehmite particulate. It is found that YAG phase from the dried gel powders appears at 1000 ℃ then the pure YAG phase exists at a relatively lower sintering temperature of 1400 ℃. The smaller sizes of phosphors in the ranges of 1 - 3 μm are obtained due to the contribution of seeding effects of nano-sized alumina particles to strengthen each step of the processes. Both the excitation and emission spectra of photoluminescence of the phosphor obtained at 1400 ℃ meet well with the spectroscopic requirements of the WLED phosphors.

Effect of Preparation Process on Compressive Strength and Hydrogenation Performance of Raney-Ni/Al2O3 Catalyst

In this study, Raney-Ni/Al_2O_3 catalysts were prepared from precursors which were calcined in different atmosphere(argon and air) and leached for different time. XRD, SEM, H_2-TPR and BET techniques were introduced to characterize the catalysts, and hydrogenation of unsaturated hydrocarbons, including vinyltoluene, dicyclopentadiene and indene, was used as probe reaction to evaluate the catalytic hydrogenation performance of the catalysts. The results demonstrated that the calcination atmosphere had noticeable effects on the compressive strength and hydrogenation performance of Raney-Ni/Al_2O_3. The catalyst calcined in argon exhibited better compressive strength and catalytic performance than the one calcined in air. The compressive strength and activity stability of catalyst were also determined by the leaching time. A too longer leaching time was not conducive to improving the compressive strength and catalytic performance of catalysts. When the precursor calcined in argon was treated in a 15%(by wt.) sodium hydroxide solution at 343 K for 5 h, a catalyst with higher compressive strength(at 26.10 N/mm) was obtained and the conversion of vinyltoluene, dicyclopentadiene(DCPD), and indene could amount to more than 87.5%, 99% and even 100%, respectively, under the reaction conditions covering a temperature of 493 K, a hydrogen pressure of 2.0 MPa, a LSHV of 3.0 h^(-1), and a hydrogen/oil ratio of 200:1.

Synthesis of AIMCM-41 mesoporous molecular sieves with high stability

Mesoporous molecular sieves AIMCM-41 were synthesized by static hydrothermal crystallization using cetyltrimethylammonium bromide as template, water glass as silica source and pseudoboehmite as aluminum source. The XRD results showed that the prepared AlMCM-41 mesoporous molecular sieves had high relative crystallinity and long-range order. The relative crystallinity was greater than 27% after calcination at 900 ℃ for 2 hours and was still greater than 14% after ageing in steam at 800 ℃ for 2 hours. The results indicated that both thermal and hydrothermal stabilities of the mesoporous molecular sieves AIMCM-41 were good.