摘要：Due to their tunable acidity,shape selectivity,and excellent stability,zeolites are of great importance as solid acid materials in industrial *** the properties of the acid sites in zeolites allows for the rational design and fabrication of catalysts for target *** ether(DME)carbonylation,a critical chain-growth reaction for C1 resource utilization,is selectively catalyzed by the Brønsted acid sites within the eight-membered rings(8-MRs)of mordenite(MOR).It is anticipated that strengthening the Brønsted acidity—particularly in 8-MRs—will improve the catalytic performance of *** this work,density functional theory(DFT)calculations are first employed and the results used to design a modified MOR with stannum(Sn)and to predict the corresponding changes in *** by the theoretical studies,a series of Sn-modified MOR are synthesized via a defect-engineering and subsequent heteroatom-substitution *** partial desilication,isolated tetrahedral Sn species in an open configuration are successfully synthesized for the first time,within which tetrahedrally coordinated Al sites are *** acidic characterization is used to confirm that the acidity of the Brønsted acid sites is enhanced by the introduction of the Sn species;as a result,the sample exhibits excellent activity in DME carbonylation *** and DFT studies reveal that this strengthened acidity facilitates the adsorption of DME and reduces the activation barriers of DME dissociation and acetyl formation,accounting for the improved *** work demonstrates mechanistic insights into the promoting effects of strong acidity on DME carbonylation and offers a promising strategy to precisely control the acidic strength of zeolites.

摘要：Among the reactions catalyzed by zeolites there are some that exhibit high selectivity due to the spatial confinement effect of the zeolite *** the acidity,particularly the distribution and location of the Bronsted acid sites in the zeolite is effective for making it a better catalyst for these *** prepared a series of H-mordenite（H-MOR） samples by varying the composition of the sol-gel,using different structure directing agents and ***3-TPD and IR characterization of adsorbed pyridine were employed to determine the amount of Bronsted acid sites in the 8-membered ring and 12-membered ring *** was shown that controlled synthesis was a promising approach to improve the concentration of Bronsted acid sites in MOR,even with a low Al *** an appropriate composition of Si and Al in the sol-gel favored a higher proportion of Bronsted acid sites in the 8-membered ring *** as a structure-direct agent gave an obvious enrichment of Bronsted acid sites in the 8-membered *** of dimethyl ether was used as a probe reaction to examine the modification of the acid properties,especially the Bronsted acid sites in the 8-membered ring *** was a linear relationship between methyl acetate formation and the number of Bronsted acid sites in the 8-membered ring channels,demonstrating the successful modification of acid *** results provide information for the rational design and modification of zeolites with spatial constraints.

摘要：Zeolite catalysts,such as H-mordenite(H-MOR),are readily deactivated by coke deposition in carbonylation *** modification of H-MOR can improve its stability but can lead to an undesirable loss in catalytic ***,we report the intrinsic impact of the pyridine adsorption behavior on H-MOR and the spacial hindrance of the zeolite frameworks on dimethyl ether(DME)carbonylation at a molecular *** discovered that acid sites at O2 positions,located on common walls of eight-membered ring(8-MR)side pockets and 12-MR channels,were active in DME carbonylation,but were unfortunately poisoned during pyridine *** functional theory calculations revealed that the pyridine-poisoned acid sites at the O2 positions could be easily regenerated due to the spacial hindrance of the zeolite ***,they can be facilely regenerated by proper thermal treatment,which induces 60%promotion in the catalytic activity along with a high *** findings demonstrate the determining role of O2 positions in H-MOR for DME carbonylation and provide a new avenue for the rational design of other efficient zeolite-relevant catalytic systems.

摘要：乙醇作为一种绿色清洁的燃料替代品和油品添加剂,在全球有广泛的市场需求.利用合成气经乙酸甲酯(ma)合成乙醇的工艺路线,因其原子经济性、产品选择性高、反应条件温和等优势而备受关注.其中,二甲醚(DME)羰基化是该路线的关键步骤之一.研究证实,具有8元环(8-MR)孔道结构的硅铝酸盐微孔分子筛可以在较低的反应温度下高选择性催化二甲醚羰基化反应.目前,研究者已经对丝光沸石(MOR)、镁碱沸石(FER)等分子筛进行了全面深入的分析,但对SSZ-13等菱沸石(CHA型)的研究有限,缺乏SSZ-13上主、副反应催化机理的阐释,并且忽略了沸石独特的笼状结构在反应中的空间限域效应.本文结合实验和理论计算确定了SSZ-13分子筛催化DME羰基化的活性位点,并探究了孔道的限域效应.通过负载具有不同尺寸的Na^(+)和Cs^(+)实现了对不同通道中Brönsted酸位点(BAS)的选择性屏蔽.酸性质表征和密度泛函理论(DFT)计算结果表明,在较低的负载量下,Na^(+)优先取代SSZ-13的6元环(6-MR)中的BAS,而Cs^(+)由于其较大的离子半径只能与8-MR中的BAS发生交换,从而实现了对SSZ-13不同孔道中酸分布的调控.负载不同金属量以及金属种类的样品活性研究表明,当6-MR中BAS减少时,DME转化率基本不变;而当8-MR中BAS被离子交换时,DME转化率明显下降.随后,将未经金属改性的、具有不同硅铝比的母体SSZ-13样品的ma生成速率与其8-MR中BAS的数量相关联,发现两者呈较好的线性关系,说明SSZ-13的8-MR中BAS为DME羰基化的活性中心.同时,DFT计算了DME在不同孔道BAS上的解离能,结果表明DME更容易在8-MR的BAS上解离从而进行后续反应.随后,探究了SSZ-13笼的空间限域效应对主副反应的影响机制.通过比较金属负载量相近的Na/H-SSZ-13和Cs/H-SSZ-13上CO插入甲氧基形成烯酮的反应势垒,证实了较大尺寸金属离子的引入增加了主反应速控步的能垒.为了揭示空间限域对副反应的影响,比较了反应后催化剂的热重、气质联用等表征结果,并利用密度泛函理论计算了副反应的关键物种(七甲基苯正离子)在Na/H-SSZ-13和Cs/H-SSZ-13上的吸附能,证实了SSZ-13的笼状结构体积是影响ma选择性的关键因素.金属负载后SSZ-13笼空间减少,可以有效地抑制副反应关键物种的形成,从而提高主反应选择性.综上,本文不仅对SSZ-13分子筛催化二甲醚羰基化反应机理进行了全面解析,并通过实验设计,改变了SSZ-13分子筛的孔道结构和笼结构空间,突出了分子筛限域效应在二甲醚羰基化反应中的重要作用.本文研究结果为设计具有较高选择性的沸石催化剂提供一定的参考.

摘要：为贯彻落实党中央、国务院关于防范化解金融风险、健全金融法治的决策部署,人民银行和相关部门共同推进金融稳定立法工作,取得积极进展。近期,十三届全国人大常委会第三十八次会议对《金融稳定法(草案)》进行了首次审议,并向社会公开征求意见。本刊特开设“金融稳定立法研究”专栏,与各方分享关于金融稳定立法的理论基础、主要思路、制度设计、国际经验等方面研究成果,供关心金融稳定立法的相关单位和各界人士参阅,以期交流碰撞思想火花,进一步夯实立法工作基础。

摘要：高端氢化石油树脂应用广泛,市场需求逐年增加,如何实现高效生产高品质氢化石油树脂是该领域研究的重点。高品质氢化石油树脂的生产主要是采用催化加氢技术,开发高效稳定的加氢催化剂是关键的技术环节。本文针对催化剂加氢效率低、树脂分子扩散与吸附困难、加氢反应条件苛刻等问题,重点综述了近年来研究者为解决上述难点在催化剂金属活性组分组成、几何与电子结构、载体形貌与孔结构设计等方面的研究成果。提出催化剂中金属活性位点的分散度、位点分布情况、价态调控及复合金属间的协同作用是调控催化剂性能的关键。同时,对目前石油树脂加氢催化剂活性位点设计、反应机理、催化剂失活再生机制等方面进行总结并展望催化剂的未来发展方向。

摘要：在气相偶联合成草酸酯工艺过程中,亚硝酸甲酯(MN)再生过程与偶联反应有效匹配是实现整个系统绿色无污染的关键,也是影响草酸酯合成工业放大过程的关键一步。对于MN再生过程的工艺优化和宏观动力学方面进行了较多研究和报道,而对MN再生过程的数学模拟研究较少。通对MN再生过程中发生的主要化学反应进行分析简化,并结合MN再生反应动力学参数,在填料塔中建立了MN再生反应数学模型,并计算了主要工艺参数对MN收率的影响。模拟结果表明,随温度升高、气体流速增大、N2体积分数增大,MN的收率减小,液体流速增大和NO/O2摩尔比增大,MN收率增大。通过实验验证了该模型的准确性,MN收率的模拟结果与实验数据的最大相对偏差为-4.39%,为MN再生反应过程的设计和操作提供了理论依据;最后,对于两种不同的NO和O2混合方式进行了比较,通过模拟计算比较了这两种不同操作方式对MN收率的影响。

摘要：CO_(2)与乙烷反应是实现碳减排目标、利用非常规能源的重要手段,符合国家重大需求和国际学术前沿。其中,二氧化碳通过“活性氧”机理、“晶格氧”机理以及“反应耦合”机理促进乙烷的活化。通过催化剂设计选择性地断裂C—H/C—C键,可以实现反应定向地按照两条路径进行——乙烷干重整反应(DRE)和乙烷氧化脱氢(ODH)。综述了DRE和ODH两类反应的热力学、反应物活化机制和催化剂研究进展,分析了催化剂均存在产物选择性低、易烧结、积炭问题的主要影响因素以及催化剂设计和改进策略,并对该研究未来的发展方向进行展望。

摘要：对氧化羰基化法合成绿色化学品有机碳酸酯的研究概况进行了综述,着重介绍了有机碳酸酯的性质和用途、催化剂的开发、反应机理和工艺过程的研究进展。在现有的非光气法合成有机碳酸酯的工艺路线中,氧化羰基化法生产相对安全、原子经济性高、副产物为水,符合绿色化学的原则,具有很好的发展前景。开发设计高效、稳定的催化剂,进一步加强对该工艺多方位的研究,具有非常重要的科学和现实意义,对我国大力发展煤化工和一碳化工将起到推动作用。

摘要：采用固定床积分反应器,研究了自制的负载型钯系催化剂上CO气相催化偶联主、副反应的宏观动力学模型.所采用的催化剂是经过模式1000h连续运转、性能稳定的1.5mm×(3～5)mm圆柱状催化剂.在适宜的反应条件下测定了动力学实验数据,并采用一维拟均相模型建立了微分方程组.使用了幂函数宏观动力学模型,采用RungeKutta法解微分方程组,并用单纯形法确定动力学模型参数,同时进行了残差分析和统计检验.结果表明,所得的动力学模型与实验数据吻合良好,可以为草酸二乙酯合成反应器设计和放大提供依据.