硫化的MoO_3/γ-Al_2O_3上甲烷化反应活性规律的研究

CO甲烷化是降低城市煤气中CO含量和增加热值的较好方法之一。镍、钌等过渡金属催化剂的硫中毒问题很难解决,因而近些年来对能抗硫中毒的钼基催化剂有了些研究,尽管这类催化剂在常压下的活性并不高。本文测定了不同硫化条件下MoO_3/γ-Al_2O_3催化剂的活性及硫钼原子比,並对催化剂甲烷化活性规律作了研究。     

Synthesis of a Polymer-bound Sensitizer and its Application in the Photoisomerization of trans-Vitamin D_3 to cis-Vitamin D_3

The photochemistry of the vitamin D family and their precursors has been the subject of extensive studies for many years1-4. Most of the studies focus on the photoisomer- ization of 7-dehydrocholesterol and that of tachysterol to previtamin D3, which is of commercial importance in the synthesis of vitamin D34, 5. Recently the cis/trans isomerization of vitamin D analogs (Scheme 1) draws attention because of its importance in the synthesis of hydroxylated vitamin D metabolites6. However, o…     

Solid-phase Synthesis of-Haloaldehydes from Polymer-supported 4-(Phenylseleno)morpholine

Polymer-supported reagents for organic synthesis are enjoying a renewed popularity with the emergence of combinatorial chemistry in recent years1. 4-(Arylseleno)morpholines formed in situ are useful -seleno-introducing reagents for saturated aldehydes2. -Sele- noaldehydes, as a frequently used intermediates, can be converted into -haloaldehydes by halogenating reaction3. However, organic selenium reagents always have a foul smell and are quite toxic, which is often problematic in organic sy…     

Evaluation of Transient Absorption Spectra of N, N, N, N- Tetra - ( p -methylphenyl ) - 4, 4- diamino - 1, 1- diphenyl Ether ( TPDAE ) for Electron Transfer from TPDAE to Fullerenes ( C_(60) / C_(70) ) by Laser Flash Photolysis

Fullerenes C60 and C70 have high electron affinity ( 2.6 - 2.8 ev ) and readily form anions on electronchemical reduction1, which were famous as electron acceptor in photo-excitation because of symmetrical shape, large size, and properties of its p - electron system2. After observation of molecular ferromagnetism3 in the tetrakis (dimethylamino ) ethylene salt of C60 as well as the occurrence of ultra-fast photoinduced electron transfer within the dimethyl aniline - C60 complex4, prompted us…     

OFDMA中继系统中基于QoS保证的资源分配算法

研究了 OFDMA 中继下行链路通信系统中的动态资源分配问题,提出了一种可以保证用户最低 QoS 需求的资源分配算法.首先在简化资源优化问题的过程中,采用等功率分配方法以降低算法复杂度,然后通过拉格朗日松弛优化方法推导出了子载波分配和中继选择最优解,并在此基础上引入用户速率权衡因子,根据速率权衡因子越大的用户,越具有选择子载波和中继的优先权这一准则进行子载波分配和中继选择.仿真结果表明:新算法能够获得较高的系统容量,同时也能很好地保证不同用户的最低速率需求.     

Synthesis and Crystal Structure of Triethyl 1,2,2-triphenylpyrrolidine-3,4,5-tricarboxylate,A Proline Derivative

１ＩＮＴＲＯＤＵＣＴＩＯＮＩｎｒｅｃｅｎｔｙｅａｒｓ，ｏｕｒｒｅｓｅａｒｃｈｇｒｏｕｐｈａｓｓｔｕｄｉｅｄｓｙｓｔｅｍａｔｉｃａｌｙｃｙｃｌｏａｄｄｉｔｉｏｎｒｅａｃ ｔｉｏｎｓｏｆｔｈｅＣ＝Ｎｄｏｕｂｌｅｂｏｎｄｓｉｎｔｈｅｂｅｎｚｏｈｅｔｅｒｏａ...     

不同阳离子Y分子筛上金属络合物的吸附和分解 Ⅱ.Co(CO)_3NO吸附和分解的红外光谱表征

采用红外光谱表征了含不同阳离子的Ｙ分子筛上Ｃｏ（ＣＯ）３ＮＯ的吸附和分解及其和阳离子的作用．结果表明，Ｃｏ（ＣＯ）３ＮＯ吸附后主要形成Ｃｏ（ＣＯ）ｘＮＯ（ｘ＝２，３），并出现热稳定性较高的Ｃｏ（ＮＯ）２＋２．产生Ｃｏ（ＮＯ）２＋２的机制和最终分解产物与分子筛阳离子的性质有关．ＮａＹ上Ｃｏ（ＣＯ）ｘＮＯ歧化产生少量Ｃｏ（ＮＯ）２＋２，分解产物主要为Ｃｏ（０）；ＣｏＹ中Ｃｏ２＋的存在部分避免了Ｃｏ（ＣＯ）ｘＮＯ的歧化，分解得到的Ｃｏ（０）含量较高；ＮｉＹ，尤其ＣｕＹ阳离子和吸附物种发生电子转移，形成ＮＯ＋中间物种，氧化Ｃｏ（０）产生Ｃｏ（ＮＯ）２＋２，分解产物为Ｃｏ（０）和Ｃｏ（Ⅱ）的混合物．