Effects of surface oxide species and contents on SiC slurry viscosity

The disadvantageous effects of colloidal SiO2 layer and micro-content of metal oxide adsorbed on SiC powder surface on SiC slurry stable dispersion were studied, and the novel method to avoid this disadvantage was proposed. By acidwashing, on the one hand, because the maximum Zeta potential of SiC powder increases to 72.49 mV with the decreasing content of metal oxide adsorbed on the SiC powder surface, the repulsion force between SiC powders that dispersed in slurry is enhanced, thus the SiC powder can be fully dispersed in slurry. On the other hand, after HF acidwashing, with the OH^- group adsorbed on SiC powder surface destroyed and replaced by the Fion, the hydrogen bond adsorbed on the OHgroup is also destroyed. Therefore, the surface property of the SiC powder is changed from hydrophilic to hydrophobic; H2O that adsorbed on SiC powder surface is released and can flow freely, and it actually increases the content of the effective flow phase in the slurry. These changes of SiC powder surface property can be proved by XPS and FTIR analysis. Finally, the viscosity of SiC slurry is decreased greatly, and when the viscosity of the slurry is lower than 1 Pa·s, the solid volume fraction of SiC powder in the slurry is maximized to 61.5 vol.%.

An Alternative to Flare Gas Processing:A Feasibility Study of Natural Gas to Liquid Processes

The quantities of gas released into the environment during the extraction and processing of crude oil,by flaring,constitute a vast source of mineral wealth which can be used to produce other useful products.The processes studied in this paper,as alternatives to the above problem,are the ones used in Shell Pearl Qatar project and Oryx GTL project.Both projects produce liquid fuels,mainly naphtha and diesel,in addition to more special fuel such as kerosene.This paper is a feasibility study of a project that makes use of the flare gas from the State of Texas,U.S.A.,as a feedstock to a process similar to either Shell Pearl Qatar project,or Oryx GTL project.The objective of this study is to determine the price range for crude oil over which an investment to similar projects can be profitable.An MS Excel Model was developed in order to perform calculations having as a variable the crude oil price and taking into account all the process and project’s financial data.The results of this model showed that a project similar to Shell Pearl Qatar remains profitable in crude oil price above$57.76/barrel,while a project similar to Oryx GTL remains viable for crude oil price over$31.4/bbl.In the price range$55-$60/barrel,the payout of the corresponding to Shell Pearl Qatar project will be in about 15.2 years and 3.3 years for a project similar to Oryx GTL.Finally,using the financial principles of this study we can apply them to any process in order to determine under what conditions will remain viable.

Air-tolerant direct reductive N-methylation of amines using formic acid via simple inorganic base catalysis

The construction of N-methyl amine moieties is an important reaction that has found numerous applications.Development of new methylation agents that are more environmentally benign than classical agents,such as iodomethane and methyl sulfate,is still highly desirable.Herein,we report a convenient protocol for direct reductive N-methylation of amines using formic acid as the methylation agent via simple inorganic base catalysis.The present protocol operates under transition-metal-free and air-tolerant conditions.Both the catalyst,K2 HPO4,and the reductant,polymethylhydrosiloxane(PMHS),are cheap and easily separable from the crude reaction product mixture.Mechanistic investigations suggest that the reaction occur through the formation of an acetal inte rmediate followed by the C-N bond formation.