The last two decades saw the emergence of a new multi-source, multi-market fuel, Dimethyl Ether or DME. Prior to 1990, DME had only found limited commercial use as an aerosol propellant along with propane and butane as a green replacement for the chlorofluoro-hydrocarbons which were outlawed because of their detrimental impact on the ozone layer. DME is an environmentally benign, non-toxic, biodegradable product with physical properties similar to LPG. Global DME annual production capacity is approximately 10 million metric tons and actual market use is reported to be about 3 million metric tons - a remarkable increase from the 200,000 metric tons market demand in the early 2000s. Nearly all of the DME is produced in China from coal-derived methanol via the well known catalytic dehydration process where two molecules of methanol react to form one molecule of DME and one molecule of water. DME is the fastest-growing methanol derivative, yet is still an emerging business with lots of upside opportunities combined with significant challenges. A number of other DME plants are in different stages of development around the world including Egypt, Middle East and Indonesia, all of them natural gas based. Sweden is the leader in the development of bio-DME produced through the gasification and conversion of black liquor, a byproduct in Sweden's paper and pulp industry.Nearly all of today's DME is used as a blend stock for LPG which in turn is primarily used for cooking and heating. At blending levels below 20 vol %, the existing LPG blending facilities, local distribution infrastructure and end-use equipment can be used with minimal (if any) modifications - making for easy marketing. Currently, efforts are underway to commercialize DME as a high-quality diesel alternative. Technical issues such as new fuel injection systems and new fuel additives have been solved and solutions are currently being tested in fleets. This review will describe the history, status and future of DME as a global fuel alternative and how it has and will be changing the global methanol industry. (C) 2012 Elsevier B.V. All rights reserved.

CO/SiO2 catalysts were prepared by aqueous cobalt nitrate impregnations of silicas with different surface areas to study the effect of the support surface area on the reactions occurring during impregnation and calcination and to define the stage and mode of metal-support interactions. TPR analyses of samples calcined in dry air showed the presence of various quantities of cobalt silicate species, while cobalt silicate formation was not discernible by other analytical techniques. Our conclusion, confirmed in our later studies, is that cobalt silicate does not form during impregnation or calcination, but is created during the reduction in the TPR instrument. Because of these and other ambiguities of the TPR analyses, in our continuing studies we preferred alternative analytical approaches.These studies on the calcination stage resulted in the following unusual findings: (1) X-ray photoelectron spectroscopy revealed drastic decreases in the surface cobalt concentration after calcination of high surface silicas impregnated with cobalt nitrate solutions. (2) Infrared spectroscopy indicated much less than expected Co3O4 formation upon calcination if high surface area silica was the support. (3) A method was devised to calculate the surface areas of individual components in mixtures. The calculations indicated about 20% surface area losses for the silica in calcined catalysts. (4) Scanning electron micrographs of a calcined catalyst on high surface area silica support showed smaller-sized decorations around the larger silica particles. Energy-dispersive X-ray analysis of the decorations showed Si as major, and Co as a minor component. Pure Co3O4 phases were not found by EDX analyses of these decorations. These four seemingly unrelated findings are attributed to a common cause: silica migration and weak bond formation between CoO and SiO2. The extent of surface area losses (i.e. the extent of silica migration) is about an order of magnitude greater in CoOx-SiO2 catalysts than in analogously treated SiO2. The migration of silica must have occurred in a relatively short time period during the thermal decomposition of cobalt nitrate, while simultaneous migration and oxidation of CoO to Co3O4 aggregates also occurred. The CoO species intercepted by SiO2 were unable to oxidize, resulting in reduced quantity of Co3O4 formation. The extensive migration of silica is attributed to strong attraction between SiO2 and CoO species, inducing the removal of silicic acid or silica molecules from the silica surface. (c) 2006 Elsevier B.V. All rights reserved.

Co/SiO2 catalysts were prepared by both impregnation and precipitation techniques and analyzed by IR, TPR, XRD, and BET methods at intermediate stages of their preparation to define the stage and mechanism of cobalt silicate formation. To prove that reducing conditions can lead to cobalt silicate, one part of a catalyst prepared by impregnation of silica with cobalt nitrate was calcined in air at 350°C, and another part in H2–N2 atmosphere at the same temperature. Infrared spectra revealed the presence of Co–O–Si absorption in the sample exposed to reducing atmosphere. Cobalt silicate formation is postulated to be a reaction between migrating silicic acid and hydrated cobalt hydroxide generated in the reduction process.

The surfaguide is a waveguide-based electromagnetic-surface-wave launcher that allows sustaining long plasma columns using microwaves. Its electrodynamic characteristics are examined experimentally and theoretically in the perspective of achieving an efficient plasma source without any need for impedance matching retuning as operating conditions are varied over a broad range. The plasma source design and its modelling using equivalent-circuit theory are described and a simple procedure is provided to determine the optimum dimensions of the surfaguide that maximize the transfer of microwave power to plasma. As an example, with an optimized surfaguide, the reflected power in an N-2 discharge at atmospheric pressure stays below 3% for powers in the 2 - 6kW range and gas flow rates in the 30 - 150 l min(-1) domain under varying concentrations (< 2%) of admixed gases such as SF6, O-2 and argon.

The monetization of the world's large, remote gas reserves is the main driver for the advancement of GTL technologies where GTL has become synonymous for Fischer Tropsch (FT) technologies. Looking to other gas derived liquids beyond GTL-FT, the conversion of natural gas into oxygenates, the methanol anchored product family, is a chemical business today which is poised to transition into a high volume fuel and chemical business. At the 6(th) Natural Gas Conversion Symposium in 2001, the promise of oxygenates centering around methanol and DME for power generation, domestic home cooking/heating, transportation, as a hydrogen carrier and as an economical chemical intermediate, was presented [I]. The focus of this paper is the significant progress since 2001 in the global efforts to commercialize gas-to-liquids technologies for producing oxygenates primarily methanol and DME. Another oxygenate, DMM (dimethoxymethane) and its homologs, poly-oxomethylenes, have potential as gasoline and diesel fuel additive, respectively.

This paper reviews the status of the gas-to-liquids (GTL) industry | including current commercial plants, announced projects and the technologies that are likely to be implemented in these future projects. Today, only 35,000 B/D of GTL products (0.1% of market) are manufactured from commercial gas-based plants. Advances in technology have lowered the cost of plants to the point where GTL plants can be protable at crude oil prices of 16/B. The advanced stage of development of several proposed GTL projects and attractive integrated economics, for both the gas eld and plant, show that GTL can be a signican t alternative for monetizing natural gas in the 21st century. GTL technologies includes more than Fischer{Tropsch technology and extends to other liquid fuels, especially in the oxygenate family (methanol, dimethyl ether, etc.).

Today, natural gas conversion is the basis of a moderately sized, predominantly chemical business whose primary products are ammonia and methanol. A major focus of natural gas conversion R&D over the last few decades has been the manufacture of conventional, yet cleaner transportation fuels. However, Gas To Liquids technology includes more than Fischer Tropsch technology and extends to other liquid fuels, especially in the oxygenate family (methanol, Dimethyl Ether [DME], etc). The focus of this paper will be the promise of oxygenates for power generation, domestic home cooking, transportation, and as economical chemical intermediates.

The most significant cost associated with partial oxidation of methane to syngas is that of the oxygen plant. In this paper, we offer a technology, based on dense ceramic membranes, that uses air as the oxidant for methane conversion reactions, thus eliminating the need for the oxygen plant. Certain ceramic materials exhibit both electronic and ionic conductivities (of particular interest is oxygen-ion conductivity). These materials transport not only oxygen ions (functioning as selective oxygen separators) but also electrons back from the reactor side to the oxygen/reduction interface. No external electrodes are required, and, if the driving potential of transport is adequate, the partial oxidation reactions should be spontaneous. Such a system will operate without an externally applied potential. Oxygen is transported across the ceramic material in the form of oxygen ions, not oxygen molecules.Recent reports in the literature suggest that dense ceramic membranes made of these mixed conductors can successfully separate oxygen from air at flux rates that could be considered commercially feasible. Thus, these membranes have the potential to improve the economics of methane conversion processes [1-5].In principle, the dense ceramic materials can be shaped into hollow-tube reactors, in which air passes over the outside of the membrane and methane flows through the inside. The surfaces can also be reversed. The membrane is permeable to oxygen at high temperatures, but not to nitrogen or other gases. Thus, only oxygen from air can be transported through the membrane to the inside of the reactor surface, where it reacts with methane. Other geometric forms, such as honeycombs or corrugations, of the reactor are possible and can provide substantially greater surface areas for reaction [6].

For several years Amoco has been involved in research and development work on the synthesis of liquid fuels from natural gas. In a recent collaborative work with Haldor Topsoe S/A, AVL LIST GmbH and Navistar, Amoco has identified Dimethyl Ether (DME) as a new, ultraclean alternative fuel for diesel engines. DME can be handled like LPG, an important alternative transportation fuel. Preliminary engine test data for DME, showing emission levels better than the California 1998 ULEV standards, were recently reported at the 1995 SAE conference in Detroit, Michigan.DME is today manufactured from methanol and is primarily used as an aerosol propellant due to its environmentally benign characteristics. Haldor Topsoe has developed a process for direct production of DME from natural gas, coal or biomass. The process can be used for large scale (about 40,000 BSD diesel equivalent) manufacture of DME from natural gas using predominantly single-train process units. In this paper, we will provide an overview of the attractiveness of DMF as an environmentally and customer-friendly diesel fuel option.