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One-step synthesis of methylmethacrylate from methacrolein over Keggin-type heteropoly compounds
Xiaojun Guo,Chongpin Huang,Biaohua Chen 한국화학공학회 2008 Korean Journal of Chemical Engineering Vol.25 No.4
One-step synthesis of methylmethacrylate (MMA) using heteropoly compounds (HPCs) as catalysts was demonstrated by feeding a mixture of methacrolein (MAL), air, water, nitrogen and MeOH (methanol). The HPCs with different counter-ions, such as H1.7Cs1.5Cu0.25As0.1PMo11VO40 (CsPMo11VO40), H1.7La0.7Cu0.25As0.1PMo11VO40 (LaPMo11VO40) and H1.7K1.5Cu0.25As0.1PMo11VO40 (KPMo11VO40), were studied in oxidation of MAL, esterification of methacrylic acid (MAA) and one-step synthesis of MMA from MAL, respectively. The selectivity of MAA was up to 45.7% and MMA was 44.6% with 93.3% MAL conversion over CsPMo11VO40.
Catalytic activity of Cu/MgO in liquid phase oxidation of cumene
Shuai Xu,Jie Zhang,Biaohua Chen,Chongpin Huang 한국화학공학회 2009 Korean Journal of Chemical Engineering Vol.26 No.6
Cumene was oxidized with air as the oxidant and Cu/MgO as the catalyst. Cu/MgO with different compositions was prepared by co-precipitation and then characterized by X-ray diffraction (XRD), H2-temperature programmed reduction (H2-TPR) and X-ray photoelectron spectroscopy (XPS). The characterization results showed that CuO dispersed on MgO well in the cases that the Cu content in Cu/MgO was 1% by molar. In this catalytic system, MgO did not only act as the supporter, but also as the catalyst to activate the tertiary C-H of cumene. The conversion of cumene was increased by using CuO as the promoter on MgO catalyst. The cumene conversion and cumene hydroperoxide (CHP) selectivity were in a trade-off relationship because cumene oxidation was subject to the decomposition of CHP. Thus, the effects of the operating variables were investigated and the relevant mechanism was discussed.
Chongpin Huang,Jie Zhang,Biaohua Chen,Jianwei Li,Yingxia Li 한국화학공학회 2008 Korean Journal of Chemical Engineering Vol.25 No.5
Alkylation of isobutane and butene was carried out in a batch unit using 1-butyl-3-methylimidazolium chloride (BMIC)-aluminium (III) chloride (AlCl3) ionic liquid as catalyst. The effects of additives of butyl thioalcohol and ethyl thioether on the properties of ionic liquids for alkylation were investigated. Improvement of production distribution with high yields of isooctane and selectivity of TMP under a mild reaction condition was observed after addition of butyl thioalcohol. Moreover, the effects of operating variables were investigated and the mechanism was discussed.
Meng, Weijuan,Li, Hongbo,Li, Jianwei,Chen, Biaohua Korean Chemical Society 2011 대한화학회지 Vol.55 No.4
지글러-나타 촉매를 사용하여 에틸렌을 중합함으로써 다양한 공단량체의 종류와 조성을 갖는 이중 분자량 분포의 고밀도 폴리에틸렌이 합성되었다. 이들의 구조와 물성을 GPC, NMR, DSC, 인장 측정기를 이용하여 연구하였다. 에틸렌/1-헥센 공중합체가 에틸렌/1-부텐 공중합체보다 비슷한 조성을 가질 경우 높은 인장강도와 파단연신율을 가짐을 확인 하였다. 분자량은 고분자의 공단량체 비율이 증가할수록 감소하였다. 짧은 곁사슬은 결정화도에 영향을 주어 결과적으로 이중 분자량 분포를 갖는 고밀도 폴리에틸렌의 모폴로지와 기계적 물성에 영향을 미쳤다. SSA로 처리 후 다수의 발열 곡선이 관찰되었으며 이는 주로 에틸렌 배열길이와 라멜라 두께의 불균일성에 기인한다. 분포지수의 차이로부터 공단량체의 조성이 높은 폴리에틸렌의 SCB 분포가 균일도를 향상시킴을 알 수 있었다. Bimodal high-density polyethylenes with different comonomer type and content were synthesized by polymerization of ethylene using Ziegler-Natta catalyst. Their structure and properties were studied using GPC, NMR, DSC and tensile test. It was found that ethylene/1-hexene copolymer exhibits higher tensile strength and elongation at break than that of ethylene/1-butylene copolymer with similar comonomer content. The molecular weight decreases as the comonomer content of the polymer increases. Short chain branching affects the crystallinity and thus the morphology and consequently the mechanical properties of the corresponding bimodal high-density polyethylenes. After SSA treated, the multiple endothermic peaks were observed. Multiple endothermic peaks are mainly attributed to the heterogeneity of ethylene sequence length and lamellar thickness. The difference of broadness index indicates that SCB distribution of polyethylene containing higher comonomer content has improved uniformity.
Jianwei Li,Guanjie Mi,Jie Zhang,Biaohua Chen 한국화학공학회 2010 Korean Journal of Chemical Engineering Vol.27 No.6
Based on the information from GC-MS on-line measurement and thermodynamic analysis, the reaction network of gas-phase hydroxylation of benzene with nitrous oxide over Fe-ZSM-5 zeolite was systematically investigated. The main reactions and side reactions were identified, and a kinetic reaction network was proposed as follows:benzene+N2O→phenol→CO/CO2. According to the mechanism, the experimental results were interpreted reasonably. The hydroxylation kinetic experiments were carried out in an isothermal integral microreactor under the conditions of n(benzene)/n(N2O)=8-12, T=663-763 K and atmospheric pressure. Based on the reaction network proposed, the parameters in the rate model of power-law were estimated by means of Gauss-Newton optimal method with the Levenberg-Marquardt modifications, and the results were in good agreement with the experimental data.
Catalytic oxidation of 1,3-diisopropylbenzene using imidazolium ionic liquid as catalyst
Shuai Xu,Jie Zhang,Jia Liu,Biaohua Chen,Chongpin Huang 한국화학공학회 2009 Korean Journal of Chemical Engineering Vol.26 No.4
Peroxidation of alkylaromatics is the key step in the synthesis of phenols. Different imidazolium ionic liquids were investigated for the oxidation of cumene. The selectivity of cumene hydroperoxide (CHP) increased with different ionic liquids in the order [C4mim]Cl<[C4mim]Br<[C4mim]BF4<[C4mim]OH. This finding could be interpreted as being due to the partial decomposition of CHP by the acidic proton of the imidazolium cation. Thus [C4mim]OH was chosen as the catalyst for the oxidation of 1,3-diisopropylbenzene to corresponding hydroperoxides and its derivatives. The catalytic performance of [C4mim]OH was also better than that of the traditional catalyst NaOH. Furthermore, the effects of the operating variables were investigated and the mechanism was discussed.
Ionic liquid/ZIF-67 derived Co9S8-SNC catalyst for oxygen reduction reaction in alkaline electrolyte
Gao Qiuyue,Li Guoru,Kofie Gideon,Chen Biaohua,Yin Fengxiang 한국탄소학회 2024 Carbon Letters Vol.34 No.3
A series of ZIF-67-C-IL catalysts were prepared using ZIF-67 and 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([BMIM]NTf2) ionic liquid as precursors. The structure of the catalysts was characterized by XRD, TEM, SEM and XPS. The catalytic performance of the catalysts for the oxygen reduction reaction (ORR) was evaluated in a three-electrode system. The results confirmed that the high-temperature treatment of the precursors resulted in the formation of N, S co-doped carbon-encapsulated Co9S8 nanoparticles. To create N, S co-doped carbon coated Co9S8 nanoparticle catalysts, ionic liquids are used as sulfur and nitrogen sources. The catalytic activity of ORR can be improved using N, S co-doped carbon to prevent the aggregation of Co9S8 nanoparticles. Graphitized and N, S co-doped carbon shells are optimal for achieving high activity stability. Optimal 600-ZIF-67-C(1:1.5)-30IL catalytic activity was observed for ORR. The half-wave potential of ORR was 0.88 V vs. RHE in 0.1 mol L−1 KOH, with a limit current density of 4.70 mA cm−2. Similar ORR electrocatalytic activity was observed between this catalyst and commercial Pt/C (20 wt%).