In Situ IR Spectroscopic Study on the Hydrogenation of 1,3-Butadiene on Fresh Mo_2C/γ-Al_2O_3 Catalyst

The surface species formed from the adsorption of 1,3-butadiene and 1,3-butadiene hydrogenation over the fresh Mo2C/γ-Al2O3 catalyst was studied by in situ IR spectroscopy. It is found that 1,3-butadiene adsorption on the Mo2C/γ-Al2O3 catalyst mainly forms π-adsorbed butadiene(πs and πd) and σ-bonded surface species. These species are adsorbed mainly on the surface Moδ+(0<δ<2) sites as evidenced by co-adsorption of 1,3-butadiene and CO on the fresh Mo2C/γ-Al2O3 catalyst. The IR spectrometric analysis show that hydrogenation of 1,3-butadiene over fresh Mo2C/γ-Al2O3 catalyst produces mainly butane coupled with a small portion of butene. The selectivity of butene during the hydrogenation of 1,3-butadiene over fresh Mo2C/γ-Al2O3 catalyst might be explained by the adsorption mode of adsorbed 1,3-butadiene. Additionally, the active sites of the fresh Mo2C/γ-Al2O3 catalyst may be covered by coke during the hydrogenation reaction of 1,3-butadiene. The treatment with hydrogen at 673 K cannot remove the coke deposits from the surface of the Mo2C/γ-Al2O3 catalyst.

Polymerization of 1,3-Butadiene Catalyzed by Cobalt(Ⅱ) and Nickel(Ⅱ) Complexes Bearing Pyridine-2-imidate Ligands

Cobalt and nickel complexes （la-ld and 2a-2d, respectively） supported by 2-imidate-pyridine ligands were synthesized and used for 1,3-butadiene polymerization. The complexes were characterized by IR and element analysis, and complex la was further characterized by single-crystal X-ray diffraction. The solid state structure of complex la displayed a distorted tetrahedral geometry. Upon activation with ethylaluminum sesquichloride （EASC）, all the complexes showed high activities toward 1,3-butadiene polymerization. The cobalt complexes produced polymers with high cis-1,4 contents and high molecular weights, while the nickel complexes displayed low cis-l,4 selectivity and the resulting polymers had low molecular weights. The catalytic activities of the complexes highly depended on the ligand structure. With the increment of polymerization temperature, the cis-1,4 content and the molecular weight of the resulting polymer decreased.

Oxidative Dehydrogenation of 1-Butene to 1,3-Butadiene Using CO2 over Cr-SiO2 Catalysts Prepared by Sol-gel Method

A series of Cr-SiO2 catalysts with a Cr content（mass fraction） ranging from 0.5% to 9% was prepared by a sol-gel method. The catalysts were characterized by XRD, N2 adsorption, EDX elemental mapping, Raman spectros- copy, UV-Vis spectroscopy, XPS and H2-TPR, and their catalytic behavior in the dehydrogenation of 1-butene to 1,3-butadiene（BD） using CO2 as a soft oxidant was studied. The initial BD yield is well correlated with the amount of Cr6~ in the fresh catalysts. The highest BD yield of ca. 34% is achieved on the catalysts with 5%--9% Cr at 600 ~C -1 -1 and weight hourly space velocity（WHSV） of 4.5 g＇geat＇h ~ The promoting effect of CO2 on the BD yield was ob- served, which can be attributed to the reaction coupling between a simple dehydrogenation of 1-butene and the re- verse water-gas shift reaction as well as regaining the oxidation state（lattice oxygen） of reduced Cr3＋ species due to the mild oxidation ability of CO2. The Cr-SiO2 catalyst exhibits higher BD yield than the Cr catalyst supported on SBA-15, which is attributed to the higher amount of Cr6＋ present on the former catalyst.

Conversion of Bioethanol to Olefins over ZrO_(2) Catalyst

Ethylene and 1,3-butadiene are important organic chemical raw materials.Petroleum hydrocarbon cracking is the most widely used method for ethylene fabrication worldwide.In this study,the use of a ZrO_(2) catalyst,which can be easily synthesized,for the efficient conversion of bioethanol to ethylene and 1,3-butadiene was analyzed.X-ray diffraction,transmission electron microscopy,temperature-programmed desorption,and Fouriertransform infrared spectroscopy analyses were used to evaluate the surface properties of ZrO_(2).The selectivity of ZrO_(2) toward ethylene and 1,3-butadiene was as high as 98.2%.Catalyst selectivity toward dehydration or dehydrogenation products depends on the nature of the weak acid-base catalytic sites,whereas high-strength base and intermediate-strength acid catalytic sites selectively yield ethylene.

一种胶粘剂的裂解GC-MS分析

目前胶粘剂广泛应用于木材加工、建筑、轻纺工业、交通运输、电工工业、机械工业、医疗卫生、日用生活、军事工业等各个领域,已成为不可缺少的重要材料之一,因此对各种胶粘剂的分析就显得十分重要.……