Coal liquid, pretreatment

Table III. Distributions in Hydrotreatment of Pretreated Primary Coal Liquids...

Taking advantage of its high separation strength, a combination of SEC with MS enhances the capability of MS and makes it possible for the analysis of coal liquids. SEC can be used as a coal liquid sample pretreatment method prior to GC-MS. For SEC, 1-methyl-2-pyrrolidinone (NMP) is often used as eluent. Analytical result for a coal liquefaction extract sample prepared from SEC by GC-MS showed that only the pentane-soluble components could be analyzed [16] the larger aromatic molecules identified by SEC to be present were lost in the GC column. The molecular weight of the aromatics analyzed in the coal liquids were up to 352 with very few aliphatics. 

Solid/liquid separation is important at all stages and depends on the extent of coal cleaning during pretreatment, depolymerization of coal macromolecules at the dissolution stage, and catalyst durability through the catalytic process. 

Gas phase studies were performed at 0.1 MPa total pressure with a flow rate of loo cc/min H2 and loo cc/min He (Linde). The helium stream was diverted through a saturator containing the liquid reactant UAL (Aldrich) such that its volume fraction in the inlet to the reactor was 0.5%. The gas hourly space velocity was 120 lh g1 catalyst. Prior to reaction, the catalyst was pretreated at 673 K for at least 2 hours following a 1 K/min rise to the reduction temperature. The reactor was coaled under... 

Hydrocarbonization processes are characterized by three primary independent variables - temperature, hydrogen pressure, and coal type - and five other, important independent variables -solid residence time, gas residence time, reactor configuration, coal pretreatment, and catalyst impregnation. Control of these variables permits control, over a wide range, of (1) the relative yields of liquid, gaseous, and solid products, (2) the quality of one or more of these products, (3) hydrogen consumption, and, ultimately (4) product cost. 

Hydrocarbonization yields may also be influenced by catalyst impregnation and coal pretreatment. For example, the yields of liquid and gasious products may be substantially increased by impregnation of the feed coal with ZnCl2 or other catalysts. (3)... 

A modem direct coal liquefaction plant can produce about 0.5-0.6t of liquid fuel from every ton of dry coal. In the cases where the hydrogen supply is also produced from coal, the overall system can produce about 11 of liquid fuel from every 3—4t of coal. China Shenhua Coal Liquefaction Co. Ltd is currently building a 20,000 bbl/day direct coal liquefaction plant in Inner Mongolia, China. The economic viability of this large-scale direct coal liquefaction remains to be revealed. Economic analysis performed in 19903 showed that the process of the two-stage conversion of CTL has a product cost of 38 per barrel. Several areas, such as improved pretreatment and cleaning methods, novel catalysts, and improved hydrocarbon recovery, were identified as ways to lower the cost further.1... 

At this point, it is worthy of note that the formation of water by the interaction of hydrogen with the oxygen species in the coal is considered by many researchers to be wasteful in terms of hydrogen consumption and, therefore, alternate means for the pretreatment of coal to ranove all (or part) of the oxygen prior to hydrogenation to liquids (Chapters 18 and 19) are always worthy of consideration. And yet, there may be benefits to such treatment. 

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