M.J. Chomón

Influence of the type of solvent on coal liquefaction with different catalysts

Abstract The liquefaction behaviour of a series of solvents in coal liquefaction both without catalyst and with two catalysts, red mud (an Fe 2 O 3 catalyst) and CZMFA2 (a CoZnMo/Al 2 O 3 ) catalyst), was evaluated. Three H-donor solvents (tetralin, 9,10-DHA and 1,2,3,4-THQ), three non-donor solvents (naphthalene, anthracene and phenantrene) and two industrial type solvents (anthracene oil and creosote oil) were tested. The experiments were conducted in a 250 ml autoclave, with 10 g of a subbituminous A coal, 30 g of solvent, 425 °C, 17 MPa operating pressure, 1 hour reaction time and 400 rpm stirring speed. The liquefaction products were fractionated into oils, asphaltenes and preasphaltenes using pentane, toluene and THF as extractive solvents. The behaviour of a solvent is greatly influenced by the type of catalyst used and viceversa, the catalyst effect depends on the solvent utilized. Industrial type solvents can give better coal conversions than strong H-donor solvents if appropriate catalysts are used

COAL LIQUEFACTION WITH ANTHRACENE OIL. INFLUENCE OF SOLVENT PRETREATMENT, TEMPERATURE, CATALYST AND PRESSURE

ABSTRACT The effect of solvent pretreatment, temperature, a CoMo/Al2O3 catalyst and pressure on coal liquefaction with anthracene oil has been evaluated. The experiments were conducted in a 500 ml autoclave with 10 g of a Spanish subbituminous A coal. 30 g of solvent, 1 hour reaction time and 400 rpm stirring speed. The liquefaction products were fractionated into oils, asphaltenes and preasphaltenes using pentane, toluene and THF as extractive solvents. The behaviour of anthracene oil as coal liquefaction solvent is very much enhanced by prehydrogenating it and by the addition ot an active catalyst. The influence of temperature depends on the operating conditions such as solvent pretreatment, catalyst, pressure etc. The addition of an active catalyst greatly improves conversion and the quality of the liquefaction products and diminishes repotimerization reactions. Hydrogen pressure is essential for coal liquefaction with anthracene oil, although over 16 MPa no further increase in coal conversion is observed.

DIRECT HYDROGENATION OF A SPANISH LOW RANK COAL. THE EFFECT OF PROCESS VARIABLES

ABSTRACT The effect of operating conditions on the liquefaction behaviour of a Spanish lignite was studied using a 250 ml stirred autoclave, and the following operating conditions (except otherwise specified): 400 °C, 1 hour, 3.5 MPa initial (cold) H2 pressure, 400 rpm and 40 g/10 g tetralin/coal charge. The liquefaction products were fractionated into oils, asphaltenes, preasphaltenes and solid residue using pentane, toluene and THF as extractive solvents The influence of temperature was explored in the 300–475 °C range, observing little further improvement in liquefaction yields over 400 °C, and retrogressive reactions over 450 °C. The effect of time was studied from 0 to 180 minutes and was concluded that 1 hour is an appropriate period for liquefying a black lignite, since there is little further conversion for longer times. The influence of pressure and gas type was studied using 0, 3.5 and 7.0 MPa initial (cold) pressure of H2 and of N2, and the effect of stirring using 0 and 400 rpm. Little influen...

VARIATION OF TEMPERATURE EFFECT WITH HYDROGEN SUPPLY IN NON-CATALYTIC COAL LIQUEFACTION

ABSTRACT A Spanish subbituminous coal was subjected to non-catalytic liquefaction with tetralin in a 250 ml stirred autoclave. The operating conditions used were: one hour reaction time, 17 MPa operating pressure and 400 r.p.m, stirring speed. The liquefaction products were fractionated into oils, asphaltenes, preasphaltenes and solid residue by a solvent extraction technique using pentane, toluene and THF as extractive solvents. It was found that the influence of temperature on coal liquefaction yields and product distributions varies with the amount of donatable hydrogen. Total coal conversion increases with temperature, when very high tetralin/coal ratios are used On the contrary, when 1/1 ratio is used, conversion does not seem to depend on temperature, and appears to be limited by the amount of liquid medium available as physical solvent. At intermediate tetralin/coal ratios,conversion generally increases with both factors: temperature and amount of solvent. However, retrogressive reactions are obser...

ELEMENTAL COMPOSITION OF ASPHALTENES FROM COAL LIQUEFACTION

The elemental composition (C, H, N, S, O) of asphaltenes isolated from coal liquefaction experiments carried out at different temperatures and tetralin/coal ratios has been determined. The liquefaction experiments were conducted in a 250 ml autoclave, with 10 g of a Spanish subbituminous A coal, for 1 hour, and at 17 ± 1 MPa operating pressure and 400 rpm stirring speed. The liquefaction products were fractionated into oils, asphaltenes and preasphaltenes using pentane, toluene and THF as extractive solvents. The % S and % O are lower in asphaltenes than in coal, while the % C and % N are higher and % H depends on the temperature and tetralin/coal ratio used. On the other hand asphaltenes % C decreases, and % H and % O increase as the tetralin/coal ratio is raised at every temperature except 475 °C, while % S and % N do not have a clear variation.

Influence of operating conditions on the effect of catalysts in coal liquefaction

Publisher Summary This chapter presents liquefaction yields obtained with several catalysts when different solvents, solvent/coal ratios, and temperatures are used. The influence of the mentioned operating conditions on catalysts effects is analyzed. The main functions fulfilled by catalysts are promoting coal structure cracking and helping to hydrogenate the free radicals formed either by H-transfer through the solvent or by the promotion of the direct reaction of hydrogen (H 2 ) gas with coal. A Spanish sub-bituminous A coal is liquefied in anthracene oil and in tetralin, without catalyst, with red mud and with a CoZnMo/A1 2 O 3 catalyst at 425, 450, and 475°C and using 3/1 and 2/1 solvent/coal ratios. There are significant influences of operating conditions on catalysts effects, and there are important relationships among such influences.

IRON COMPOUNDS AND C0-Mo/Al2O3 CATALYSTS: ACTIVITY IN DIRECT HYDROGENATION OF A SUBBITUMINOUS A COAL WITH AN H-DONOR SOLVENT

Abstract The effectiveness of different catalysts were compared in coal liquefaction experiments using a 250 ml stirred autoclave, 10 g of a Spanish Subbituminous A coal, 1 hour reaction time, 17 MPa operating pressure, 400 rpm stirring speed, at 425 and 450 °C with 2/1 and 3/1 tetralin/coal ratio. The liquefaction products were fractionated into oils, asphaltenes, preasphaltenes and solid residue using pentane, toluene and THF as extractive solvents. Three iron-oxide containing catalysts: red mud, an Fe2O3 aerosol and Cottrell ash (by-product of the aluminium industry); and three alumina supported catalysts: CMA, which is a conventional CoMo/Al2O3 catalyst, CZMA which in addition contains Zn as a second promoter, and CZMFA which has the alumina acidified with fluorine and also contains Zn, were compared. It has been reported that the addition of Zn and of F enhances the HDS, cracking, hydrocracking or hydrogenating activities of CoMo/Al2O3 catalysts in experiments with pure compounds. The objective of th...

EFFECT OF THE CHARACTERISTICS AND DEGREE OF FILLING OF THE AUTOCLAVE ON COAL HYDROLIQUEAFACTION

Publisher Summary This chapter discusses the effect of the characteristics and degree of filling of the autoclave on coal hydroliqueafaction. It explores the effect of the degree of filling of the reaction system on coal hydroliquefaction with tetralin and presents a comparison of the results obtained in a 250 ml autoclave and in a 35 ml tubing bomb. The liquefaction experiments were conducted in two batch reactor systems including a 250 ml autoclave and a 35 ml tubing bomb. The former was electrically heated at a rate of about 11°C min−1 and magnetically stirred at 400 rpm, while the latter was very quickly heated by means of a hot air fluidized sand bed and was neither stirred nor shaken. The autoclave at 1 h reaction time gives better results than the tubing bomb at 1 h reaction time, but almost the same results as the tubing bomb at 2 h. It is found that the longer heating and cooling periods of the autoclave are responsible for the higher conversions obtained in such system, when similar conditions are used in both reactors.