Comparative study on pyrolysis of bamboo in microwave pyrolysis-reforming reaction by binary compound impregnation and chemical liquid deposition modified HZSM-5

The deactivation of catalyst is a significant reason for its limited application during the catalytic fast pyrolysis(CFP)process.To reduce the coke formation,binary compound impregnation(BCI)and chemical liquid deposition(CLD)were used to modify HZSM-5 catalysts.At the same time,the self-designed microwave reactor separated the pyrolysis of bamboo and catalytic upgrading of primary vapor,which made the catalytic effect more thorough.Experimental results indicated that CLD used TiO 2 deposition to cover external acid sites,while BCI by phosphorus-nickel could cover and partly destroy superficial acid sites through two different ways.Within the scope of the loaded amount studied,the yield of aromatic hydrocarbons in the oil phase increased at first and then decreased,while the coke formation reduced continuously.BTX(benzene,toluene and xylene),the most valuable product in bio-oil,drastically increased by 39.1%and 22.6%respectively over the CLD and BCI modified catalysts.Considering the catalytic performance as well as cost,CLD over HZSM-5 has more advantages in the CFP process to upgrade bio-oil.

Chemical Liquid Phase Deposition of Thin Aluminum Oxide Films

Thin aluminum oxide films were deposited by a new and simple physicochemical method called chemical liquid phase deposition (CLD) on semiconductor materials. Aluminum sulfate with crystallized water and sodium bicarbonate were used as precursors for film growth, and the control of the system抯 pH value played an important role in this experiment. The growth rate is 12 nm/h with the deposition at [Al2(SO4)3]=0.0837 molL-1, [NaHCO3]=0.214 molL-1, 15 ℃. Post-growth annealing not only densifies and purifies the films, but results in film crystallization as well. Excellent quality of Al2O3 films in this work is supported by electron dispersion spectroscopy, Fourier transform infrared spectrum, X-ray diffraction spectrum and scanning electron microscopy photograph.

Growth of centimeter scale Nb_(1−x)W_(x)Se_(2) monolayer film by promoter assisted liquid phase chemical vapor deposition

Two-dimensional(2D)transition-metal dichalcogenide materials(TMDs)alloys have a wide range of applications in the field of optoelectronics due to their capacity to achieve wide modulation of the band gap with fully tunable compositions.However,it is still a challenge for growing alloys with uniform components and large lateral size due to the random distribution of the crystal nucleus locations.Here,we applied a simple but effective promoter assisted liquid phase chemical vapor deposition(CVD)method,in which the quantity ratio of promoter to metal precursor can be controlled precisely,leading to tiny amounts of transition metal oxide precursors deposition onto the substrates in a highly uniform and reproducible manner,which can effectively control the uniform distribution of element components and nucleation sites.By this method,a series of monolayer Nb_(1−x)W_(x)Se_(2)alloy films with fully tunable compositions and centimeter scale have been successfully synthesized on sapphire substrates.This controllable approach opens a new way to produce large area and uniform 2D alloy film,which has the potential for the construction of optoelectronic devices with tailored spectral responses.

Microstructure and properties of SiC gradiently coated C_f/C composites prepared by a RCLD method

The SiC gradiently coated carbon fiber/carbon （Cf/C） composites were prepared by a two-step rapid chemical liquid deposition （RCLD） method. The microstructure and properties of the composites were investigated using X-ray diffraction, scanning electron microscopy together with energy dispersive X-ray analysis, bending tests, and oxidation tests. The experimental results show that the surface layer of the composites is composed of SiC, pyrocarbon, and carbon fibers. Their inner area consists of pyrocarbon and carbon fibers. The SiC content gradiently decreases with increasing distance from the outer surface to the center of the composites. Furthermore, the thickness of the SiC layer increases with increasing tetraethylorthosilicate content and deposition time. SiC coatings have no significant influence on the bending strength of the composites. However, the oxidation resistance of the composites increases with increasing thickness of the SiC layer.