Synthesis of ethylene, methanol and formaldehyde by partial oxidation of methane.

1987年，我们研究了甲烷氧化偶联成乙烷和乙烯的反应。我们的代表性研究结果和结论如下：1.氧化钐是甲烷和氧气合成C_2烃(乙烷和乙烯)的最高活性催化剂。在750℃时，当C2烃选择性较高(%)时，C_2烃的时空产率可达3mol/g·h。2.添加NiO的LiCl制得乙烯具有良好的选择性。添加LiCl的作用是抑制宿主NiO对甲烷和C_2烃深度氧化的催化活性，促进CH_4、C_2H_6、C_2H_4的后续反应。3.上述催化剂的动力学结果可以很好地解释为反应机理，即反应的决定步骤是吸附在催化剂表面的分子氧物种从CH_4中提取H。4.在LiNiO_2催化剂上，C_2-烃是通过催化剂…的氧化还原生成的再来一次。LiNiO_2的晶格氧原子对C_2-烃的形成具有特别的活性和选择性。甲烷分子在Ni^&lt；3+&gt；-O^&lt；2-&gt；位上容易解离，其速率决定步骤是这些位上的CH3基团偶联生成乙烷。1988年，我们研究了甲烷部分氧化制甲醛和甲醇。1.添加FeNbO_4的B_2O_3是甲烷和氧气合成甲醛反应中活性最高、选择性最好的催化剂。FeNbO_4提供了断裂C-H键和产生甲醛所必需的活性晶格氧原子。B_2O_3通过减少甲醛的分解和深度氧化，提高了对甲醛的选择性。2.动力学结果表明，在高温&600℃下，CH_4分子撞击到催化剂表面时发生振动激发，活性氧物种从这些CH_4分子中提取H。该模型也适用于除LiNiO_2以外的各种催化剂上的甲烷氧化偶联反应。

In 1987 we studied on oxidative coupling of methane into ethane and ethylene. Our representative results and conclusions are as follows; 1. Samarium oxide was the most active catalyst for the formation of C_2-hydrocarbons (ethane and ethylene) from methane and oxygen. At 750 C, the space time yield of C_2-hydrocarbons reached to 3 mol/g.h, when the selectivity to C_2-hydrocarbons was fairly high (64%). 2. LiCl added NiO produced ethylene with excellent selectivity. The roles of the added LiCl are to inhibit the catalytic activity of the host NiO for deep oxidations of both methane and C_2-hydrocarbons and to enhance the successive reaction CH_4 C_2H_6 C_2H_4. 3. The kinetic results observed with above catalysts can be explained well in terms of the reaction mechanism that the rate determining step is the abstraction of H from CH_4 by molecular oxygen species adsorbed of the catalyst surface. 4. In the case of LiNiO_2 catalyst, C_2-hydrocarbons were formed through the redox of the catal … More yst. The lattice oxygen atoms of LiNiO_2 are especially active and selective for the formation of C_2-hydrocarbons. CH_4 molecules disociate easily on Ni^<3+>-O^<2-> sites and the rate determining step was the coupling of CH_3 groups on these sites to form ethane.In 1988 we studied on partial oxidation of methane into formaldehyde and methanol. 1. B_2O_3 added FeNbO_4 was the most active and selective catalyst for the formation of formaldehyde from methane and oxygen. FeNbO_4 supplies reactive lattice oxygen atoms which are necessary for breaking C-H bond and producing formaldehyde. B_2O_3 improves the selectivity to formaldehyde by reducing both the decomposition and deep oxidation of the formed formaldehyde. 2. The kinetic results suggest that the CH_4 molecules are vibrationally excited upon their impact onto the catalyst surface at high temperatures >600 C and that the active oxygen species abstract H from these CH_4 molecules. This model for CH_4 activation can also be applicable to oxidative coupling of methane over various catalysts except for LiNiO_2. Less