Electronic and geometric effects of alkali promoters in CO hydrogenation over K/Mo2C catalysts

When potassium salts such as K₂CO₃, KOH, CH₃COOK, and K₂S were added to Mo₂C, the promoted catalysts showed high selectivities to alcohols and light olefins in CO hydrogenation at 573 K and 1.0 MPa. However, K₂SO₄ and KCl caused only slight increase in olefin selectivity with negligible alcohol formation. These two groups of promoters showed different physical and chemical states during the reaction as observed by AES, EDS, EPMA, IR and transient reaction behavior. This difference accounted for the observed difference in selectivity.     

碳多孔体中碳化硅晶须的原位生长

根据碳化硅晶须生长的特定驱动力要求，通过实验和建立气相传输模型研究了碳多孔体中碳化硅晶须原位生长的条件。模型和实验研究均表明，温度和多孔体表面气相组成对多孔体内的晶须原位生长起决定作用；体内附加反应的设置可以改变晶须生长所要求的温度和表面气相条件。     

气流粉碎B4C粉末的掺碳活化烧结研究

开展了气流粉碎B4C粉末(比表面积2．53m2/g)的掺碳烧结实验，研究了掺碳剂种类、掺碳量、烧结温度、比表面积等对B4C烧结密度的影响．结果表明，掺碳显著促进B4C的烧结；在炭黑、葡萄糖和酚醛树酯三种掺碳剂中，掺入酚醛树酯可以获得最高的烧结密度；并且最佳的掺碳量为3％-5％C．B4C 3％C(酚醛树酯)分别经2200和2250℃烧结后的密度为92．1％TD和94．4％TD．若采用振动球磨B4C粉末(8．30m2／g)进行掺碳烧结实验，则可使2200℃的烧结密度提高到95．6％TD．     

铌改性V_2O_5催化甲醇乙醇一步合成异丁醛催化剂的催化性能研究

用Nb2O5和Nb(OH)5对甲醇、乙醇一步合成异丁醛(IBA)V2O5催化剂进行了改性研究。实验结果表明,两者都能增加V2O5催化剂的活性和选择性,综合性能最佳的催化剂为w(Nb2O5)为8%的Nb2O5/V2O5催化剂和w(Nb(OH)5)为18%的Nb(OH)5/V2O5催化剂,这两种催化剂的乙醇转化率分别为95.39%和96.39%,IBA选择性分别为47.87%和55.35%,较V2O5催化剂IBA选择性分别提高了21.25%和40.20%。XRD结果表明,在Nb2O5/V2O5的XRD图谱上有Nb2O5衍射峰,而Nb(OH)5/V2O5催化剂几乎未检测到Nb2O5衍射峰,说明该催化剂煅烧后生成的Nb2O5几乎以无定形形式存在于催化剂体系中,从而使Nb(OH)5/V2O5催化剂表现出了更好的活性和选择性。     

Influence of Precipitates Size and Distribution on Room Temperature Mechanical Properties and Accelerated Creep of X20CrMoV121

The effect of microstructure on creep resistance of the low carbon chromium steel X20CrMoV121 after 100‐hours of static‐load test at a temperature of 580 °C and constant stress of 170 MPa was investigated. The specimens for the experiments were extracted from steam pipes of a steam power plant and heat treated. The effect of isothermal annealing on the microstructure and hardness as well as the kinetics of the precipitation of the carbide particles were determined.     

高温气冷堆控制棒B4C芯块的研制

阐述了用电弧炉碳热还原法制备核级B4C粉末、经热压烧结制备高温气冷堆控制棒B4C芯块的研制过程，研究了添加剂对制备B4C芯块的影响。     

AI_4C_3 Hydration Thermochemical Analysis for Burned Carbon-containing Refractories with Al

In this paper, X-ray diffractogram analysis and SEM observation of Al$ C$ formed at high temperature from carbon-containing refractories ivith Al have been carried out. Aluminum added to carbon-containing refractories reacts with C(s) to form Al^ C^(s) gradually during heating from 600 'C to 1200^0 . It is considered that the interlocked structure of Al^ C-$ plate crystals promotes the outstanding increase of hot modulus of rupture of carbon-containing refractories with Al. The HMOR of carbon-containing refractories added with Al additive from 0 to 5wt% increases by 2.8 times being from 6.5MPa to 18.2MPa. After a thermochemical calculation for hydration reaction processes ofAl^C^ and H^O (g), the equilibrium partial pressure chart ofH^O (g) in H^O-A^C^-Al^ OH)} system vs various temperatures has been attained . The H2 0 (g) partial pressure in the air needed for the Al^ C3 hydration reaction is no more than 10 ~ 18 atm at the temperature below 120t . It is considered that the burned carbon-containing re     

Prefabrication of SiC whiskers through induction of carbon fiber

A new way to prepare SiC whiskers through the induction of carbon fiber was suggested. With the processing steps of opening furnace firstly and then shutting it, rice hall, as the only raw material, was carbonified to get excess quantity of Si in rice hull. After a certain catalyzer was added, SiC whiskers were prepared by means of the induction of carbon fiber. The component and morphology of the whisker were analyzed by XRD, SEM and TEM. The results reveal that the diameters of the whiskers range in 0.5-2 μm and their lengths in 100-500 μm. The whiskers are straight β-SiC crystals with smooth surface. The whisker is homogeneous and its productivity is 100%. Two kinds of formation mechanisms, both VLS mechanism and vapor formation mechanism, are involved during the growth of the whiskers. But the vapor formation mechanism relatively plays a key role.     

铌和钨(001)面熔化的分子动力学模拟

采用改进分析型嵌入原子方法(MAEAM),对铌、钨晶体的(001)面预熔和熔化过程进行分子动力学模拟。通过计算不同温度的原子位置、层原子密度、层结构因子、径向分布函数等物理量,研究(001)面的微观结构随温度的变化。结果表明,(001)面在低于其完整晶体的熔化温度出现预熔。另外,通过将该面预熔摩尔分数对温度进行拟合发现,可以近似地预测(001)面的预熔过程。