Effects Of Low Temperature Catalytic Pretreatments On Coal Structure And Reactivity In Liquefaction Technical Progress Report October 1991 December 1991
Download Effects Of Low Temperature Catalytic Pretreatments On Coal Structure And Reactivity In Liquefaction Technical Progress Report October 1991 December 1991 full books in PDF, epub, and Kindle. Read online free Effects Of Low Temperature Catalytic Pretreatments On Coal Structure And Reactivity In Liquefaction Technical Progress Report October 1991 December 1991 ebook anywhere anytime directly on your device. Fast Download speed and no annoying ads. We cannot guarantee that every ebooks is available!
| Author | : |
| Publisher | : |
| Total Pages | : 95 |
| Release | : 1992 |
| Genre | : |
| ISBN | : |
Low-temperature catalytic pretreatment is a promising approach to the development of an improved liquefaction process. This work is a fundamental study on effects of pretreatments on coal structure and reactivity in liquefaction. The main objectives of this project are to study the coal structural changes induced by low-temperature catalytic and thermal pretreatments by using spectroscopic techniques; and to clarify the pretreatment-induced changes in reactivity or convertibility of coals in the subsequent liquefaction. This report describes the progress of our work during the first quarterly period. Substantial progress has been made in the spectroscopic characterization of fresh and THF-extracted samples of two subbituminous coals and fresh samples of three bituminous coals using cross-polarization magic angle spinning (CPMAS) solid state 13C NMR and pyrolysis-GC-MS techniques. CPMAS 13C NMR and pyrolysis-GC-MS provided important information on carbon distribution/functionality and molecular components/structural units, respectively, for these coal samples. Pyrolysis-GC-MS revealed that there are remarkable structural differences in structural units between the subbituminous coals and the bituminous coals. Furthermore, significant progress has been made in the pretreatments and spectroscopic characterization of catalytically and thermally pretreated as well as physically treated Wyodak subbituminous coal, and temperature-staged and temperature-programmed thermal and catalytic liquefaction of a Montana subbituminous coal.
| Author | : |
| Publisher | : |
| Total Pages | : |
| Release | : 1994 |
| Genre | : |
| ISBN | : |
| Author | : |
| Publisher | : |
| Total Pages | : 50 |
| Release | : 1994 |
| Genre | : |
| ISBN | : |
In this quarter, progress has been made in the following two aspects: The influences of temperature, dispersed Mo catalyst, and solvent on the liquefaction conversion and composition of products from low-rank coals; and the hydrous pyrolysis of a lignite and spectroscopic characterization of its structural transformation during the hydrous pyrolysis. The analytical work described in this quarter also represents molecular-level characterization of products. The purpose of the first part of the work described in this quarter is to study the influences of temperature, solvent and dispersed Mo catalyst on the liquefaction conversion and chemical composition of the products. Many specialty chemicals, including one- to four-ring aromatics, could potentially be produced by liquefying coal. To achieve this goal, not only a high coal conversion but also a desirable product distribution is necessary. Therefore, it is of great importance to understand the structural changes of the coal during reaction and to investigate the conditions under which the aliphatics or aromatics can be removed from the macromolecular structure of coal. This quarterly report also describes the hydrous pyrolysis of Potapsco lignite and spectroscopic characterization of its structural transformation during the hydrous pyrolysis. This work has some implications both on the structural changes of low-rank coals during pretreatment and on the geochemical reactions during coalification stage. Vitrinite, a major component of most coals, is derived from degraded wood in ancient peat swamps. Organic geochemical studies conducted on a series of coalified wood samples derived mostly from gymnosperms have allowed the development of a chemical reaction series to characterize the major coalification reactions which lignin, the major coal-producing component of wood, undergoes.
| Author | : |
| Publisher | : |
| Total Pages | : 55 |
| Release | : 1993 |
| Genre | : |
| ISBN | : |
This work is a fundamental study of catalytic pretreatments as a potential preconversion step to low-severity liquefaction. The ultimate goal of this work is to provide the basis for the design of an improved liquefaction process and to facilitate our understanding of those processes that occur when coals are initially dissolved. The main objectives of this project are to study the effects of low-temperature pretreatments on coal structure and their impacts on the subsequent liquefaction. The effects of pretreatment temperatures, catalyst type, coal rank and influence of solvent will be examined. We have made significant progress in the following four aspects during this quarterly period: (1) influence of drying and oxidation of coal on the conversion and product distribution in catalytic liquefaction of Wyodak subbituminous coal using a dispersed catalyst; (2) spectroscopic characterization of dried and oxidized Wyodak coal and the insoluble residues from catalytic and thermal liquefaction; (3) the structural alteration of low-rank coal in low-severity liquefaction with the emphasis on the oxygen-containing functional groups; and (4) effects of solvents and catalyst dispersion methods in temperature-programmed and non-programmed liquefaction of three low-rank coals.
| Author | : |
| Publisher | : |
| Total Pages | : 136 |
| Release | : 19?? |
| Genre | : |
| ISBN | : |
| Author | : |
| Publisher | : |
| Total Pages | : 97 |
| Release | : 1992 |
| Genre | : |
| ISBN | : |
Low-temperature catalytic pretreatment is a promising approach to the development of an improved liquefaction process- This work is a fundamental study on effects of pretreatments on coal structure and reactivity in liquefaction. The main objectives of this project are to study the coal structural changes induced by low-temperature catalytic and thermal pretreatments by using spectroscopic techniques; and to clarify the pretreatment-induced changes in reactivity or convertibility of coals in the subsequent liquefaction. This report describes the recent progress of our work. Substantial progress has been made in the spectroscopic characterization of structure and pretreatment-liquefaction reactions of a Montana subbituminous Coal (DECS-9), and thermochemical analysis of three mw and reacted bituminous coals. Temperature programmed liquefaction has been performed on three low-rank coals both in the presence and absence of dispersed molybdenum sulfide catalyst. We also performed a detailed study of the effects of mild thermal pretreatment -- drying in air and in vacuum -- on thermal and catalytic liquefaction of a Wyodak subbituminous coal. Important information on structure and structure transformation during thermal pretreatment and liquefaction reactions of low-rank coals has been derived by applying solid-state CPMAS 13C NMR and flash pyrolysis-GC-MS (Py-GC-MS) for characterization of the macromolecular network of a Montana subbituminous coal and its residues from temperature-programmed and nonprogrammed liquefaction (TPL and N-PL) at final temperatures ranging from 300 to 425°C in H-donor and non-donor solvents. The results revealed that this coal contains significant quantities of oxygen-bearing structures, corresponding to about 18 O-bound C per 100 C atoms and one O-bound C per every 5 to 6 aromatic C.
| Author | : |
| Publisher | : |
| Total Pages | : 86 |
| Release | : 1992 |
| Genre | : |
| ISBN | : |
During this quarterly period progress has been made in the following three subjects related to the effects of low-temperature thermal and catalytic pretreatments on coal structure and reactivity in liquefaction. First, the liquefaction behavior of three bituminous coals with a carbon content ranging from 77% to 85% was evaluated spectroscopically by 13C NMR and pyrolysis/gas chromatography/mass spectrometry to delineate the structural changes that occur in the coal during liquefaction. Complementary data includes ultimate and proximate analysis, along with optical microscopy for maceral determinations. Even though these are all bituminous coals they exhibit quite different physical and chemical characteristics. The coals vary in rank, ranging from HvC b to HvA b, in petrographic composition, different maceral percentages, and in chemical nature, percent of carbon and of volatiles. It is these variations that govern the products, their distribution, and conversion percentages. Some of the products formed can be traced to a specific maceral group. Second, pyrolysis-GC-MS and FTIR techniques were used to characterize Wyodak coal before and after drying in vacuum and in air and the residues from its thermal and catalytic liquefactions. The analysis of the air-dried coal shows a decrease in the phenolic type structures in the coal network and increase in the carbonyl structures as the oxidative drying proceeds. An enhanced decrease in the carbonyl structure is observed in the liquefaction residues from the raw coal as compared to that of the vacuum dried coal. The analyses of the liquefaction residues of the air-dried coal show an increase in the ether linkages which may have a negative impact on liquefaction. The extent of the solvent adduction also increases during liquefaction with the extent of oxidation of the coal. Finally, the effects of reaction conditions were investigated on conversion of low-rank coals using a Texas subbituminous coal.
| Author | : |
| Publisher | : |
| Total Pages | : 58 |
| Release | : 1994 |
| Genre | : |
| ISBN | : |
In this quarter, progress has been made in the following two aspects: (1) spectroscopic and chemical reaction studies on the effects of drying and mild oxidation of a Wyodak subbituminous coal on its structure and pretreatment/liquefaction at 350°C; and (2) effects of dispersed catalyst and solvent on conversion and structural changes of a North Dakota lignite. Drying and oxidation of Wyodak subbituminous coal at 100-150°C have been shown to have significant effects on its structure and on its catalytic and non-catalytic low-severity liquefaction at 350°C for 30 min under 6.9 MPa H2. Spectroscopic analyses using solid-state 13C NMR, Pyrolysis-GC-MS, and FT-IR revealed that oxidative drying at 100-150°C causes the transformation of phenolics and catechol into other related structures (presumably via condensation) and high-severity air drying at 150°C for 20 h leads to disappearance of catechol-like structure. Increasing air drying time or temperature increases oxidation to form more oxygen functional groups at the expense of aliphatic carbons. Such a clearly negative impact of severe oxidation is considered to arise from significantly increased oxygen functionality which enhances the cross-link formation in the early stage of coal liquefaction. Physical, chemical, and surface physicochemical aspects of drying and oxidation and the role of water are also discussed. A North Dakota lignite (DECS-1) coal was studied for its behaviors in non-catalytic and catalytic liquefaction. Reactions were carried out at temperatures between 250 and 450°C. Regardless the reaction solvents and the catalyst being used, the optimum temperature was found to be 400°C. The donor solvent has a significant effect over the conversion especially at temperatures higher than 350°C.
| Author | : |
| Publisher | : |
| Total Pages | : 25 |
| Release | : 1992 |
| Genre | : |
| ISBN | : |
Low-temperature catalytic pretreatment is a promising approach to the development of an improved liquefaction process. This work is a fundamental study on effects of pretreatments on coal structure and reactivity in liquefaction. The main objectives of this project are to study the coal structural changes induced by low-temperature catalytic and thermal pretreatments by using spectroscopic techniques; and to clarify the pretreatment-induced changes in reactivity or convertibility of coals in the subsequent liquefaction. This report describes the progress of our work during the second quarterly period. Significant progress has been made in the spectroscopic characterization of fresh and THF-extracted samples of Wyodak subbituminous coals, catalytic and thermal low-temperature pretreatments in the absence and presence of hydrogen-donor and non-donor solvents, and the spectroscopic characterization of thermally and catalytically pretreated coals using cross-polarization magic angle spinning (CPMAS) solid-state 13C NMR, pyrolysis-GC-MS and FT-IR techniques.
| Author | : |
| Publisher | : |
| Total Pages | : 95 |
| Release | : 1992 |
| Genre | : |
| ISBN | : |
Low-temperature catalytic pretreatment is a promising approach to the development of an improved liquefaction process. This work is a fundamental study on effects of pretreatments on coal structure and reactivity in liquefaction. The main objectives of this project are to study the coal structural changes induced by low-temperature catalytic and thermal pretreatments by using spectroscopic techniques; and to clarify the pretreatment-induced changes in reactivity or convertibility of coals in the subsequent liquefaction. This report describes the progress of our work during the first quarterly period. Substantial progress has been made in the spectroscopic characterization of fresh and THF-extracted samples of two subbituminous coals and fresh samples of three bituminous coals using cross-polarization magic angle spinning (CPMAS) solid state 13C NMR and pyrolysis-GC-MS techniques. CPMAS 13C NMR and pyrolysis-GC-MS provided important information on carbon distribution/functionality and molecular components/structural units, respectively, for these coal samples. Pyrolysis-GC-MS revealed that there are remarkable structural differences in structural units between the subbituminous coals and the bituminous coals. Furthermore, significant progress has been made in the pretreatments and spectroscopic characterization of catalytically and thermally pretreated as well as physically treated Wyodak subbituminous coal, and temperature-staged and temperature-programmed thermal and catalytic liquefaction of a Montana subbituminous coal.
