A Novel Technology for Natural Gas Conversion by Means of Integrated Oxidative Coupling and Dry Reforming of Methane

A novel process concept for the oxidative coupling of methane followed by the oligomerization to liquids has been developed within the frame of the EU integrated project OCMOL. This technology is based on process intensification principles via cutting‐edge structured microreactor technology. It is also a fully integrated industrial process through the re‐use and the recycling of by‐products, in particular CO₂, at every process stage. The focus of this contribution is on the reaction engineering aspects of the core steps, i.e., catalysts, kinetics and reactor design for the methane coupling and reforming.     

Structured Raney Nickel Catalysts for Liquid‐Phase Hydrogenation

Structured catalysts consisting of metal sheets on which Raney nickel was deposited by the thermal spraying method were tested for the liquid‐phase hydrogenation of glucose to sorbitol and 2‐nitrotoluene to 2‐methylaniline, used as model reactions. Catalytic tests performed in a bench‐scale (1 L) reactor showed that the catalytic activity of Raney Ni sheets is significantly higher than the one of the pellets used for fixed‐bed applications, but lower than the activity of the powder catalyst used in slurry mode. The activity could be significantly improved when applying a two‐phase co‐current flow through a monolith. In this case, the activity was superior to the one obtained with the slurry catalyst. These results confirm the potential of Raney Ni monoliths as structured catalysts.     

Gas tight sintered material for high temperature sublimation setups

Fine powders of WC, TaC and TaC with W and WC additives were cold-isostatically pressed to ceramic discs and pressurelessly sintered at temperatures up to 2100 °C in a second step. Afterwards, the discs were tested as crucible lid under typical AlN growth conditions. The prepared discs should be gas tight and ensure a better alignment of the thermal expansion coefficients of TaC lid and AlN.Ceramic discs densified by this method reveal a relative density up to 97%. The TaC ceramic discs without additives show a microstructure with grain sizes in the range of 10-200 μm after sintering. The grain enlargement could be reduced by W and WC additives in the range of 1-5 wt.%. The results show that the AlN boules adhere only to WC lids and tungsten containing lids with W contents higher than or equal to 3 wt.%.     

Simulations of the effect of hydrodynamic conditions and properties of membranes on the catalytic performance of a fluidized-bed membrane reactor for partial oxidation of methane

In a fluidized-bed membrane reactor the selectivity of separation can be controlled by influencing the hydrodynamics of the fluidized bed. In this reactor type, with the mass transport limitation between bubbles and the emulsion phase, even with the non-selective membranes, high selectivity of separation can be achieved. This opens the possibility for applications of membrane reactors for reaction systems for which selective membranes do not exist, e.g. when Knudsen-type membranes or form-selective separation can not be applied. This paper is aimed at explaining the interaction between the selectivity of separation and the hydrodynamics of the fluidized bed by means of simulations that were performed for a fluidized-bed membrane reactor for catalytic partial oxidation of methane.     

Analysis of side group motion in O-acetyl-starch using regioselective 2-O-acetyl-starches by means of dielectric spectroscopy

The complex dielectric constant of O-acetyl-starches with regioselective and the statistical distribution of substituents at the anhydroglucose unit (AGU) are measured in an extended frequency range from 10 mHz to 2 MHz and in the low temperature range from −120 to 0°C. The experimentally determined relaxation spectra are evaluated with the well-known model function of Havriliak–Negami for relaxation processes. In the case of 2-O-acetyl-starch two significant relaxations are detected which are associated with the orientational motion of the methylolgroup at the AGU and the acetylgroup in position C-2. The activation energies are 48 and 60 kJ/mol, respectively. Owing to that assignment of relaxations at the AGU with acetylation in position C-2 has proved that it is possible to describe further relaxation processes in acetylated amylomaize starch with a statistical substitution pattern. It was found that an additional relaxation process is associated with the dynamics of the acetylgroup at the position C-6 at the AGU and characterized by a lower activation energy of 28 kJ/mol.

From the analytical point of view these results of dielectric spectroscopy analysis demonstrate that the mobility of the side groups depend significantly on the position at the AGU and the type of substituent in their frequency and temperature dependence.     

Reaction engineering studies in a polytropic fixed-bed reactor over a highly active and selective catalyst for oxidative methane coupling

The oxidative coupling of methane (OCM) was carried out in a polytropic fixed-bed reactor applying a Zr/La/Sr catalyst developed by the Neste company. Over this catalyst the OCM reaction follows a complex reaction scheme which includes primary parallel reaction steps to CO, CO₂ and C₂H₆ and consecutive reactions of ethane to ethylene or CO_x. Yield of higher hydrocarbons C₂₊ obtained with this catalyst strongly depended on reaction conditions, i.e. low partial pressures of methane and oxygen obtained by diluting the feed gas with nitrogen and high reaction temperatures promoted C₂₊ selectivity and yield. The maximum yield amounted to 21.4% (20 Vol.-% CH₄, 9 Vol.-% O₂, 71 Vol.-% N₂, T = 860°C; X_CH4 = 41.8%, S = 52.5%). This result belongs to the highest yields reported in the open literature.     

FLAC 在煤矿开采沉陷预测中的应用及对比分析

 应用FLAC2D3. 3 和FLAC3D1. 0 对河南省鹤壁矿务局4 矿开采沉陷进行了预计, 通过对比分析经典预计方法(概率积分法) 与FLAC 计算结果, 发现FLAC 能真实地模拟现场地质条件, 弥补一般经典方法不能考虑断层影响的不足, 是一种简单易行的开采沉陷预计方法。