Catalytic liquefaction

A multistage liquefaction process consisting of deashing, hydrogen-transfer liquefaction, catalytic depolymerization with FeS2, catalytic hydro-... 

Different types of other coal liquefaction processes have been also developed to convert coals to liqnid hydrocarbon fnels. These include high-temperature solvent extraction processes in which no catalyst is added. The solvent is usually a hydroaromatic hydrogen donor, whereas molecnlar hydrogen is added as a secondary source of hydrogen. Similar but catalytic liquefaction processes use zinc chloride and other catalysts, usually under forceful conditions (375-425°C, 100-200 atm). In our own research, superacidic HF-BFo-induced hydroliquefaction of coals, which involves depolymerization-ionic hydrogenation, was found to be highly effective at relatively modest temperatnres (150-170°C). 

Thermochemical Liquefaction. Most of the research done since 1970 on the direct thermochemical Hquefaction of biomass has been concentrated on the use of various pyrolytic techniques for the production of Hquid fuels and fuel components (96,112,125,166,167). Some of the techniques investigated are entrained-flow pyrolysis, vacuum pyrolysis, rapid and flash pyrolysis, ultrafast pyrolysis in vortex reactors, fluid-bed pyrolysis, low temperature pyrolysis at long reaction times, and updraft fixed-bed pyrolysis. Other research has been done to develop low cost, upgrading methods to convert the complex mixtures formed on pyrolysis of biomass to high quaHty transportation fuels, and to study Hquefaction at high pressures via solvolysis, steam—water treatment, catalytic hydrotreatment, and noncatalytic and catalytic treatment in aqueous systems. 

CTSL = catalytic/catalytic two-stage liquefaction. Approximately 6% ash. 

These reactors contain suspended solid particles. A discontinuous gas phase is sparged into the reactor. Coal liquefaction is an example where the solid is consumed by the reaction. The three phases are hydrogen, a hydrocarbon-solvent/ product mixture, and solid coal. Microbial cells immobilized on a particulate substrate are an example of a three-phase system where the slurried phase is catalytic. The liquid phase is water that contains the organic substrate. The gas phase supplies oxygen and removes carbon dioxide. The solid phase consists of microbial cells grown on the surface of a nonconsumable solid such as activated carbon. 

The second section of this volume describes several potentially new liquefaction processes which may have higher efficiencies than today s developing technologies. The theme of the Storch Award Symposium, featured throughout these six chapters, was new process potentials through the use of short-contact-time thermal processes followed by catalytic upgrading. 

It is well known that during liquefaction there is always some amount of material which appears as insoluble, residual solids (65,71). These materials are composed of mixtures of coal-related minerals, unreacted (or partially reacted) macerals and a diverse range of solids that are formed during processing. Practical experience obtained in liquefaction pilot plant operations has frequently shown that these materials are not completely eluted out of reaction vessels. Thus, there is a net accumulation of solids within vessels and fluid transfer lines in the form of agglomerated masses and wall deposits. These materials are often referred to as reactor solids. It is important to understand the phenomena involved in reactor solids retention for several reasons. Firstly, they can be detrimental to the successful operation of a plant because extensive accumulation can lead to reduced conversion, enhanced abrasion rates, poor heat transfer and, in severe cases, reactor plugging. Secondly, some retention of minerals, especially pyrrhotites, may be desirable because of their potential catalytic activity. 

The formation of these thermal fragments is necessary to catalytic liquefaction processes before the catalysts can become effective for hydrogen introduction, cracking and/or heteroatom removal (10). ... 

In catalytic coal liquefaction processes, reaction temperatures must be high in order to insure that thermal reactions disrupt the coal structure to the point that the catalyst can act on the products. 

To improve selectivity and conservation of hydrogen over present liquefaction technology in the conversion of coal to high quality liquids, we believe that thermal reactions should be kept as short as possible. Catalytic processes must be used for upgrading but should be used in a temperature regime which is optimal for such catalysts. 

Whitehurst, D.D. Mitchell, T.O. Farcasiu, M. Dickert, J.J., Jr., "Exploratory Studies in Catalytic Coal Liquefaction", Final Report from Mobil Research and Development Corporation to EPRI under Project RP-779-18, 1979. 

Table III shows the results of operating the SRT unit in the hydrogen donor mode (catalytically hydrogenated solvent) with and without the addition of Light SRC to the distillate solvent Batch I solvent was used in Run 9 A blend of Batch VI solvent and Light SRC, 70/30 weight ratio, were catalytically hydrogenated as the feed to Runs 1 and 3 The hydrogen donor capability of the solvents were measured by the Equilibrium microautoclave tests These bench-scale SRT results are rather extraordinary in respect to increased distillate yields and improvement in unit operability with addition of Light SRC In Table III the integrated yields refer to the combination of liquefaction, CSD, and catalytic hydrogenation of the solvent ...

In Wilsonville Runs 143 and 147, thermal degradation of the coal-derived products greatly affected the SRC recovery on the Rerr-McGee CSD Unit. Both runs were made at identically the same operating conditions, except in Run 143, where presumably catalytically active solids were allowed to accumulate in the liquefaction reactor, whereas in Run 147 the solids were removed. The product yields exiting the reactor for both runs were very similar however, the thermal sensitivity of the... 

In this paper the effects of kinds of coal, pasting oil, catalyst and reaction temperature on coal liquefaction are illustrated, and a few kinetic models for catalytic liquefaction of five coals carried out in an autoclave reactor are proposed. 

Catalytic hydrogenation of phenanthrene to the octahydro-stage produces both sym- and asym-isomers, although the former predominate Additionally, interconversion of the two forms tends to occur at coal liquefaction conditions. Since the... 

Stephens, H. P., and Chapman, R. N., The Kinetics of Catalytic Hydrogenation of Pyrene Implications for Direct Coal Liquefaction Processing. In Am. Chem. Soc. Div. Fuel Chem, 1983. Prepr. Pap. 28 pp. 161-168. 

Catalytic system designs, 10 88, 89 Catalytic Two-Stage Liquefaction (ITSL), 6 841, 843... 

Catalytic coal liquefaction processes do not specifically use hydrogen donor solvents although coal is introduced into the liquefaction reactor as a slurry in a recycle liquid stream. Catalyst is used as a powder or as granules such as pellets or extrudates. If powdered catalyst is used, it is mixed with the coal/liquid stream entering the reactor. Pelleted catalyst can be used in fixed bed reactors if precautions are taken to avoid plugging with solids or in fluidized bed reactors. In the latter case, the reacting system is actually a three phase fluidized bed, that is, catalyst particles and coal solids, as well as liquid, are fluidized by gas. 

NMR properties, 33 213, 274 in zeolite acidity studies, 33 279-281 removal, in catalytic liquefaction upgrading, 40 65-66... 

The experiments of nanocatalytic liquefaction of hydrogen were carried out using a platinum-supported carbon nanolayer. In the experiments, H PtClj, 6HjO or H PtClj was used as a Pt precursor. To prepare the Pt catalytic reaction nanolayer, the required amounts of H PtClj were mixed with 5 wt.% carbon prepared by burning naphthalene in air (Demirbas, 2008). 

Demirbas, A. 2008. Nano-catalytic liquefaction of hydrogen. Energy Sources Part A 30 1540-1547. 

Much of the research pursued by the authors of this paper and by their associates has involved studies of the catalytic hydrogenation of coals in the absence of solvent. The technique has been used to elucidate the mechanisms of catalytic coal liquefaction and to provide simultaneously some insight into the structure of coals. Peter Given was directly instrumental in providing the incentive for this research which has extended since 1983. Previous findings were disseminated through several publications (4-8. In this paper, some of the earlier data have been collated with more recent results (9) to provide an account of the relevance of these studies to the two-component concept. 

In this paper, a number of low-severity liquefaction regimes are considered. The influence of different H-donor and non-donor solvents on primary conversions without a hydrogen overpressure is discussed in the light of other recent work (10-131. Also, it is demonstrated that oil yields broadly increase with decreasing coal rank in both H-donor extraction and dry catalytic hydrogenation provided that retrogressive reactions are avoided in the initial stages of coal dissolution. 

Derbyshire, FJ., Catalytic Coal Liquefaction by Temperature-Staged Reaction, presented at Direct Liquefaction Contractor s Review Meeting, Pittsburgh, PA (Oct. 20-22, 1986). 

Davis, A., Schobert, H.H., and Derbyshire, FJ., Enhanced Coal Liquefaction bv Low Severity Catalytic Reactions. Technical Progress Report for the period Mar. to May, 1987, U.S. DOE/PETC Contract No. DE-FG22-86PC90910, (6/1987). 

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