摘要:

Some structural features of the dissolution products from two Turkish lignites ( Beypazari and Tuncbi-lek lignites) have been investigated with proton nuclear magnetic resonance and infra-red spectroscopies and gas chromatography. The results indicate that, in general, no substantial changes occur in the structural characteristics of the soluble products obtained from different extraction conditions. This is true especially for preasphaltene and asphaltene fractions. On the other hand, some structural differences were observed in the compositions of oil fractions especially in the neutral fraction of oils from the different experimental conditions. The neutral oils from the low temperature and short time extractions are mainly consisted of alkylated aromatics and include a very small quantity of longer chain paraffins. Whereas the oils from the extractions at high temperatures and longer times include several long straight-chain paraffins (C15 - C32) with higher quantity. Hydrogen atmosphere is moderately effective for deoxygenation of the products. Dealkylation reactions for smaller molecules are insignificant but hydrogen atmosphere is relatively effective for the dealkylation of larger molecules. Higher temperature and longer extraction period accelerate the liquid phase pyrolysis.

ISSN:0884-3759    

DOI:10.1080/08843759108942282

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

In this paper a parameter optimization technique is introduced involving a minimization algorithm. The technique is applicable to a wide range of problems involving data analysis. In particular, it is applied to the first-order initial-value problem describing the autocatalytic reaction of tar sand recovery process, as a result of which, the optimal reaction rate constants for a given set of experimental data are obtained. The analytical solution to the governing differential equation corresponding to these optimal parameter values is then shown to fit the experimental data. Numerical results are presented in graphical form for three different sets of data, and discussion and conclusions are provided subsequently.

ISSN:0884-3759    

DOI:10.1080/08843759108942283

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

There are inconsistencies in the literature regarding the role of organosulfur compounds in general, and sulfonic acids in particular, on the oxidative instability of middle distillate fuels. Comparison of published results between investigations is complicated by differences in a large number of variables. Variations in fuel composition, heteroatam distribution, reaction surface, hydroperoxide concentration, dissolved oxygen and reaction temperature all contribute to the variation in observed results. In an effort to clarify this situation, we have examined the t-butyl hydroperoxide liquid phase oxidation of hexyldisulfide in deaerated benzene.

ISSN:0884-3759    

DOI:10.1080/08843759108942284

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The biogas generation was performed using cowdung and sawdust in the ratios of 4:1 and 2:1, respectively. The experiments were also conducted using cowdung alone for the comparison purpose. The increase in the amount of sawdust in the mixture of cowdung and sawdust decreases the quantity of gas production. The production of methane up to three weeks is also effected by the amount of sawdust. The nitrogen contents increase and volatile solids decrease with the digestion of waste materials. The thermogravimetric studies of the materials support the biogas generation as the decomposition of particular part of cowdung.

ISSN:0884-3759    

DOI:10.1080/08843759108942285

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

This work focuses on the influence of changes in catalyst structure on the catalytic activity in liquid phase methanol synthesis process. Long-term methanol production experiments were performed under various reaction environments in order to investigate the relationship between the catalytic activity and the crystallite size in the methanol synthesis catalyst. The regeneration experiments were also conducted in order to reduce the crystallite size of aged catalysts by inducing metallic phase redispersion. The experimental results showed that the drop in the catalytic activity was closely linked to the growth in the crystallite size in the catalyst. The crystallite size was reduced successfully by cyclic oxidation-reduction treatments and as a result the lost activity in aged catalysts was recovered.

ISSN:0884-3759    

DOI:10.1080/08843759108942286

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Over the years, several analytical methods have been applied to various heavy crude oil residua and their processed products to understand the chemistry behind residuum upgrading processes. The ultimate aim has been to predict prccessability of specific feeds. However, few, if any analytical methods have been found which adequately perform this task. This paper examines selected processing experiments by the following techniques – clusion chromatography with element specific detection, D 2007-80 with as-phaltene precipitation (SARA) separation, hydrogen distribution and incorporation by NMR – cusses whether the analytical technique has any potential to predict prccessability

ISSN:0884-3759    

DOI:10.1080/08843759108942287

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

ISSN:0884-3759    

DOI:10.1080/08843759108942288

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor