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991.
992.
Wonsang Kwon Yecheol Rho Kensuke Kamoshida Kyung Ho Kwon Youn Cheol Jeong Jonghyun Kim Hideki Misaka Tae Joo Shin Jehan Kim Kwang‐Woo Kim Kyeong Sik Jin Taihyun Chang Heesoo Kim Toshifumi Satoh Toyoji Kakuchi Moonhor Ree 《Advanced functional materials》2012,22(24):5194-5208
Low‐temperature anionic ring‐opening homopolymerizations and copolymerizations of two glycidol derivatives (allyl glycidyl ether (AGE) and ethoxyethyl glycidyl ether (EEGE)) are studied using a metal‐free catalyst system, 3‐phenyl‐1‐propanol (PPA) (an initiator) and 1‐tert‐butyl‐4,4,4‐tris(dimethylamino)‐2,2‐bis[tris‐(dimethylamino)phosphoranylidenamino]‐2Λ5,4Λ5‐catenadi(phosphazene) (t‐Bu‐P4) (a promoter) in order to obtain well‐defined functional linear polyethers and diblock copolymers. With the aid of the catalyst system, AGE is found to successfully undergo anionic ring‐opening polymerization (ROP) even at room temperature (low reaction temperature) without any side reactions, producing well‐defined linear AGE‐homopolymer in a unimodal narrow molecular weight distribution. Under the same conditions, EEGE also undergoes polymerization, producing a linear EEGE‐homopolymer in a unimodal narrow molecular‐weight distribution. In this case, however, a side reaction (i.e., chain‐transfer reaction) is found to occur at low levels during the early stages of polymerization. The chemical properties of the monomers in the context of the homopolymerization reactions are considered in the design of a protocol used to synthesize well‐defined linear diblock copolyethers with a variety of compositions. The approach, anionic polymerization via the sequential step feed of AGE and EEGE as the first and second monomers, is found to be free from side reactions at room temperature. Each block of the obtained linear diblock copolymers undergoes selective deprotection to permit further chemical modification for selective functionalization. In addition, thermal properties and structures of the polymers and their post‐modification products are examined. Overall, this study demonstrates that a low‐temperature metal‐free anionic ROP using the PPA/t‐Bu‐P4 catalyst system is suitable for the production of well‐defined linear AGE‐homopolymers and their diblock copolymers with the EEGE monomer, which are versatile and selectively functionalizable linear aliphatic polyether platforms for a variety of post‐modifications, nanostructures, and their applications. 相似文献
993.
994.
筛选国产树脂,并与装置原进口树脂进行催化剂对比试验,结果表明:国产某型号树脂在顺酐酯化中的转化率、选择性和使用寿命方面均能满足工艺需求,部分指标优于装置原进口酯化催化剂。因此在装置酯化塔内逐步将进口树脂更换成国产树脂进行工业化试验,并不断改进和优化装置酯化塔的树脂装填方案,从而工业化应用国产树脂,降低装置生产成本,获得更好的经济效益。 相似文献
995.
本文对4#隧洞出口临近既有线施工项目的实地进行了研究,总结得出了施工的方案和办法,以及问题相应的措施。 相似文献
996.
Yongju Bang Joongwon LeeSeung Ju Han Jeong Gil SeoMin Hye Youn Ji Hwan SongIn Kyu Song 《International Journal of Hydrogen Energy》2012
A series of mesoporous nickel–alumina xerogel catalysts (denoted as CNAX) were prepared by a single-step carbon-templating sol–gel method using different amount of carbon template (X), and they were applied to the hydrogen production by steam reforming of liquefied natural gas (LNG). Textural properties of CNAX catalysts were improved with increasing the amount of carbon template. CNAX catalysts exhibited diffraction peaks corresponding to nickel aluminate phase, while CNA18 and CNA24 catalysts showed additional bulk nickel oxide phase. From TPR measurements, it was revealed that the interaction between nickel species and alumina in the CNAX catalysts became weakened with increasing the amount of carbon template. Crystallite size of metallic nickel in the reduced CNAX catalysts showed a volcano-shaped trend with respect to the amount of carbon template. In the steam reforming of LNG, CNAX (X = 0, 6, 12, and 18) catalysts exhibited a stable catalytic performance during the reaction, while CNA24 catalyst showed a significant catalyst deactivation. Crystallite size of metallic nickel served as an important factor determining the catalytic performance in the steam reforming of LNG. Initial LNG conversion and initial hydrogen yield increased with decreasing crystallite size of metallic nickel of the catalysts. Among the catalysts tested, CNA12 catalyst with the smallest crystallite size of metallic nickel showed the best catalytic performance. 相似文献
997.
Mengyin Liao Weiping Li Xiping Xi Chenglong Luo Yinxuan Fu Shuanglin Gui Zhaohuan Mai Heng Yan Cheng Jiang 《International Journal of Hydrogen Energy》2017,42(38):24090-24098
This article describes findings of the correlation between the atomic scale surface structure and the electrocatalytic performance of nanoengineered Pt-Pd/C catalysts for oxygen reduction reaction (ORR), aiming at providing a new fundamental insight into the role of the detailed atomic decorated structure of the catalysts in fuel cell reactions. Carbon-supported Pt decorated Pd nanoparticles (donated as Pt-Pd/C), with Pt coverage close to a monolayer, were prepared from a simple galvanic replacement reaction between Pd/C particles and PtCl42? at room temperature. The decorated architecture was confirmed by extensive microstructural characterization techniques, including TEM, XRD, XPS, HAADF-STEM, ICP and HS-LEIS. The catalysts were also examined for their intrinsic kinetic activities towards oxygen reduction reaction. The results have shown that the Pt-Pd/C catalysts are highly active towards molecular oxygen electrocatalytic reduction. These findings have profound implications to the design and nanoengineering of decorated surfaces of catalysts for oxygen reduction reaction. 相似文献
998.
999.
1000.
介绍中化弘润石油化工有限公司600 kt/a催化汽油加氢装置加氢催化剂RSDS-21,RSDS-22首次进行反应器外再生、重生及工业应用情况。经过器外烧炭再生及重生后,RSDS-21中碳质量分数由4.21%下降至0.52%,硫质量分数由5.60%下降至0.51%;RSDS-22中碳质量分数由4.90%下降至0.55%,硫质量分数由5.20%下降至0.84%,重生后催化剂颗粒完整。各项开工数据表明,经过硫化处理后,催化剂活性恢复较好,基本达到装置初次开工时催化剂活性水平,各项产品指标达到国标要求。反应在低温状态下进行,有利于降低产品汽油辛烷值损失,延长催化剂使用寿命。此次催化剂再生、重生效果较好,达到生产要求。 相似文献