Research on Ethylene and Propylene Formation during Catalytic Pyrolysis of Methylcyclohexane

The influence of operating parameters and type of zeolite catalysts on formation of ethylene and propylene during catalytic pyrolysis of methylcyclohexane (MCH) was studied in a laboratory fixed fluidized bed reactor. The results indicated that higher reaction temperature and lower WHSV tended to produce more ethylene and propylene, among which the reaction temperature was an important factor influencing the ethylene formation. Compared with the FAU and BEA type zeolites, the MFI structured zeolite catalyst, thanks to more acid sites and smaller pore diameter of the catalyst, was conducive to the formation of ethylene and propylene. The protonation occurred on different C—C bonds and C—H bonds in the carbon chain of MCH led to different product slates, and the protonation on C—C bonds located at naphthenic ring was favorable to the formation of ethylene and propylene.

Preparation of Nano-MnFe2O4 and Its Catalytic Performance of Thermal Decomposition of Ammonium Perchlorate

Nano-MnFe2O4 particles were synthesized by co-precipitation phase inversion method and low-temperature combustion method respectively, using MnCl2, FeCl3, Mn（NO3）2, Fe（NO3）3, NaOH and C6H8O7. X-ray diffraction （XRD）, transmission electron microscope （TEM）, Fourier transform infrared spectroscopy （FT-IR）, thermogravim-etry-differential thermal analysis （TG-DTA） and differential scanning calorimetry （DSC） were used to characterize the structure, morphology, thermal stability of MnFe2O4 and its catalytic performance to ammonium perchlorate. Results showed that single-phased and uniform spinel MnFe2O4 was obtained. The average particle size was about 30 and 20 nm. The infrared absorption peaks appeared at about 420 and 574 cm-1, and the particles were stable below 524 ℃. Using the two prepared catalysts, the higher thermal decomposition temperature of ammonium perchlorate was decreased by 77.3 and 84.9 ℃ respectively, while the apparent decomposition heat was increased by 482.5 and 574.3 J？g？1. The catalytic mechanism could be explained by the favorable electron transfer space provided by outer d orbit of transition metal ions and the high specific surface absorption effect of MnFe2O4 particles.

Maximizing the visible light photoelectrochemical activity of B/N-doped anatase TiO_2 microspheres with exposed dominant {001} facets

Anatase TiO2 microspheres with exposed dominant {001} facets were doped with interstitial boron to have a concentration gradient with the maximum concentration at the surface. They were then further doped with substitutional nitrogen by heating in an ammonia atmosphere at different temperatures from 440 to 560℃ to give surface N concentrations ranging from 7.03 to 15.47 at%. The optical absorption, atomic and electronic structures and visible-light photoelectrochemical water oxidation activity of these materials were investigated. The maximum activity of the doped TiO2 was achieved at a nitrogen doping temperature of 520℃ that gave a high absorbance over the whole visible light region but with no defect-related background absorption.

Controlling metallic Co^(0) in ZIF-67-derived N-C/Co composite catalysts for efficient photocatalytic CO_(2) reduction

An efficient photocatalytic CO_(2) reduction has been reported in ZIF-67-derived-Co nanoparticles(NPs)encapsulated in nitrogen-doped carbon layers(N-C/Co).This work demonstrates that the pyrolysis temperature is crucial in tuning the grain size and components of metallic Co^(0) of N-C/Co composite catalysts,which optimizes their photocatalytic activities.Syntheses were conducted at 600,700,and 800℃ giving the N-C/Co-600,N-C/Co-700,and N-C/Co-800 samples,respectively.N-C layers can well wrap the Co NPs obtained at a low pyrolysis temperature(600℃)owing to their smaller grains than those of other samples.A high metallic Co^(0) content in the N-C/Co-600 sample can be attributed to the effective inhibition of surface oxidation.By contrast,the surface CoOx oxides in the N-C/Co-700 and N-C/Co-800 samples cover inside Co cores,inhibiting charge separation and transfer.As a result,the N-C/Co-600 sample yields the best photocatalytic activity.The carbon monoxide and hydrogen generation rates are as high as 1.62×10^(4) and 2.01×10^(4)μmol g^(−1)h^(−1),respectively.Additionally,the Co NPs make composite catalysts magnetic,enabling rapid and facile recovery of catalysts with the assistance of an external magnetic field.This work is expected to provide an instructive guideline for designing metal-organic framework-derived carbon/metal composite catalysts.

Experimental Study of Isopropanol Dehydrogenation over Amorphous Alloy Raney Nickel Catalysts

The dehydrogenation reaction of isopropanol occurring at low temperature is of great industrial importance. It is a key procedure in isopropanol/acetone/hydrogen chemical heat pump system. An experimental investigation was performed to study the behavior of the liquid phase dehydrogenation of isopropanol over amorphous alloy Raney nickel catalysts. Un-promoted and promoted catalysts were used and their performances were compared under various catalyst amounts, acetone content in the reactant and reaction temperature ranging from 348 K to 355 K.It is found that there exists an optimum catalyst concentration which is about 0.34 g in 300 ml isopropanol. The temperature has evident effect on the reaction. The presence of activities of Fe-promoted catalyst decrease slightly compared to the un-promoted catalyst when the temperature are 348 K and 351 K. Besides, the reaction rate decreases almost linearly with the increase of acetone volume fraction in the reactant.