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Surface chemical modification of zeolites and their catalytic performance for naphthalene alkylation 总被引:2,自引:0,他引:2
Acid-catalyzed naphthalene alkylation products, such as 2,6-dialkylnaphthalenes (2,6-DAN), are industrially important compounds used to make monomers for advanced polymer materials [1]. Zeolite molecular sieves can be extensively used in many catalytic applications, specifically in naphthalene alkylations due to their high activity and stability as well as their high selectivity. The initial studies have mainly focused on gas phase alkylation of naphthalene with methanol, and only obtained th… 相似文献
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一、引 言 在空间旋转变换下,变换后的量子系统波函数|φ'〉与原来波函数|φ'〉的关系为式中Iz为组成量子系统的粒子自旋在空间转轴。方向的分量算符,θ为绕z轴的转角,可见变换后的波函数与粒子自旋有关.对费密子,当θ=2π时,旋转后的波函数附加相位因子-1,只有再旋转2π时波函数才恢复原值,即费密子具有空间旋转的4π对称性(或称旋量性).对玻色子,当θ=2π时,波函数复原,即具有空间旋转的2π对称性. 费密子的旋量性在理论上早已确立,然而其直接的实验验证直至近几年才完成.旋量性的验证涉及波函数相位的测量,有一类观测量的平均值表式中… 相似文献
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本文应用平均Hamiltonian理论讨论了异核偶极相互作用引起的场相关化学位移,对照二阶微拢论的结果,发现计入了"A"项的额外影响。说明在讨论非久期项效应时,一级平均Hamiltonian比只用二阶微扰论的结果更精确。文中,应用平均Hamiltonian理论还讨论了同核偶极相互作用产生的场相关化学位移。 相似文献
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In this paper a study of the spin lattice relaxation times of dioxane(DO) adsorbed on various charcoals is presented. Results show that the magnetziation of DO decays biexponentially (Table 1) as observed in the case of adsorbed hydrocarbons~[6]. The fast relaxing molecules are considered to be those adsorbed in micropores with radii less than 1.0 nm whose motion is restricted and slowed down, thus they form a solid like phase. However, the slow relaxing ones are those condensed in the micropores, they are free to move and form the liquid like phase. Molecules condensed in the interior of the micropores exchange rapidly with those situated in the vicinity of the pore wall according to Eq.(2).Comparison of data in Table 1 may lead to a conclusion that charcoal with greater density of surface acidic groups and greater percentage of pore capacity with radius<1.0 nm (V_(10)/V_(30)) has a greater percentage of solid like phase (P_f). Although V_(10)/V_(30) of density of surface acidic groups. It is apparent that surface acidic groups in micropores play an important role in the formation of solid like phase of DO on charcoals. It seems that DO form hydrogen bond with the surface acidic groups. It is this hydrogen bond and the hinderance effect of pores restrict the DO from moving freely, which results in the formation of the so called solid like phase. It can be found from small (0.10 ml/gC). This implies that DO vapour may first condense in the micropores having more acidic groups and higher activation energy, and then fill in other pores step by step as the adsorption process proceeds. 相似文献
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