Mineral matter catalyst

Taken together, these data suggest that both alkylation and the presence of chlorine ions contributed to the observed liquefaction reactivity enhancement. Although the data are preliminary, we believe that iron pwite and perhaps other species in the coal mineral matter may be chlorinated to form metal chlorides such as FeCU such species are known to be active coal conversion catalysts (1112). 

Solid/liquid separation is usually required at the interface of the primary and secondary stages to allow optional upgrading of the crude coal liquids of the primary liquefaction stage, by removing mineral matter, unreacted coal, heavy products, and catalysts (111, 112). Distillation, anti-solvent extraction, and centrifugation have been conventionally employed in liquefaction processes (113, 114). 

Mineral matter contaminates or coats the catalyst surface. 

More recently, there has been much concern about the possible effects of the mineral matter in coal on processes used to convert coal to other fuels such as gasification, liquefaction, and production of clean solid fuels. Not only is removing and disposing of the mineral matter a problem, but also the possible chemical effects such as catalyst poisoning, which might be expected in the methanation of gas from coal, should be considered. 

The highly fluid Pittsburgh Seam coal, on the other hand, does not require addition of a vehicle as the data of Table II show. As a matter of fact, superior results were obtained in the absence of a vehicle although the difference may arise from the fact that in one case a cleaned coal was used, i.e.9 the poorer results with the vehicle may reflect some adverse effect of the mineral matter on the hydrocracking process. Also, a somewhat lower catalyst/coal feed ratio was used in the run without a vehicle. 

It is generally appreciated that the mineral matter associated with some coals may act as a catalyst for liquefaction. A common observation is that among bituminous coals from the eastern United States, those with a relatively high mineral matter content also provide relatively high liquefaction yields. Also, addition of coal-derived mineral matter increases the liquefaction yields from those coals with low mineral matter content. The involvement of pyrite in these effects has been fairly well established. The importance of clay and/or other minerals is less well defined. 

Western subbituminous coals can be readily liquefied and desulfurized by non-catalytlc liquefaction vlth synthesis gas and steam at 400-450°C and an operating pressure of 3800-4400 psl. The mineral matter present In these coals functions as effective catalysts for promoting the water gas shift reaction and the reduction of carbonyl groups to oil soluble products. 

The effect of mineral matter present In subbituminous coals was Investigated by carrying out non-catalytlc liquefaction with hydrogen and synthesis gas. Most of the twelve coals studied could be readily liquefied to a low viscosity and low sulfur oil In the absence of added catalysts with synthesis gas at temperatures of 400-450°C and operating pressures of 3800-4400 psl. Comparison with coal liquefaction using pure hydrogen at optimum liquefaction temperature of 425°C and pressure of 3800-4000 psl resulted In lower conversions, lower selectivity to oil and a product with higher viscosity. 

Coal ash is not always a deleterious material for a process. In coal liquefaction, it has been observed that the rate is increased in the presence of pyrite. In gasification, the rate is increased in the presence of alkalies. There is limited data available on the effects of materials on combustion. Although interest in synthetic fuels from coal is quite limited at present, there is an interest in developing the technical capability to permit the production of more premium fuel types from less desirable ones. The conversion of solid coal to liquid fuels has been a very demanding process in terms of the pressures and, to some extent, the temperatures that have been used. Catalysts have been required in all cases. The catalysts have been poisoned by the sulfur and other species in the mineral matter. As a result, catalyst costs and replacement rates can be quite high. A cheap, naturally occurring catalyst that came with the coal would be of significant interest. Pyrite seems to be such a material. 

In recent years, it has been realized that mineral matter plays an important role in coal liquefaction (9-11), similar to the role of the added catalyst in the Bergius process. Several experimental techniques have been used to study the effects of minerals on coal liquefaction and to identify the specific catalytic phase (12). Most studies (12-14) strongly imply that the iron sulfides are the roost active species, and the other minerals appear to have little effect on enhancement of liquid yield or quality. 

The fifth session looked at the possibility that there may be some desirable aspects associated with the mineral matter in the coal. The mineral matter may be a catalyst for some of the current or future uses of coal. Specifically, the mineral matter could have some effect on combustion and also on future synthetic fuels efforts that could provide either gaseous or liquid fuels. 

Coke consists mainly of carbon (90-95%) and has a low mineral matter content (determined as ash residue). Coke is used as a feedstock in coke ovens for the steel industry, for heating purposes, for electrode manufacture, and for production of chemicals. The two most important categories are green coke and calcinated coke. This latter category also includes catalyst coke deposited on the catalyst during refining processes this coke is not recoverable and is usually burned as refinery fuel. 

Ahmed et al. [116] carried ont a detailed stndy with the objective of identifying the properties of activated carbons that are important for the SCR of NO they concluded that chemical properties such as surface oxides and mineral matter play a more important role than their physical properties, such as surface area and pore structure. In effect, they found that the catalyst activity correlated directly with the oxygen content of the carbon samples and inversely with their pH. These results indicate that the NO conversion is favored on more acidic carbons. They also reported that NO reduction by ammonia was negligible in the absence of oxygen. Indeed, it has been shown [117] that oxygen enhances the C-NO reaction through the formation of surface oxygen complexes, which are essential for the C-NO reaction to proceed. 

Aluminum, silicon, and iron can influence the size of the electrostatic precipitator. But, moreover, the fly ash can cause degradation of any catalyst used downstream by blocking the pores as well as causing erosion. This is in addition to any possible detrimental effects of the mineral matter in a coal conversion plant. Again, catalyst poisoning as well as adverse catalytic effects of the mineral constituents on the process may occur (Jenkins and Walker, 1978). On the other hand, any potential beneficial catalytic effects of the mineral constituents of coal (especially in relation to conversion processes) (Bredenberg et al., 1987) also need evaluation and precise definition. 

The inorganic matter within the coal can have a detrimental effect on the process. In addition to poisoning catalysts, there is the potential for leaching harmful elements from residues and ashes after disposal and certain minerals cause abrasive and chemical wear as well as clogging and buildup in the reactors (Harris and Yust, 1977 Russell and Rimmer, 1979). But there is also the suggestion that the mineral matter in coal might have catalytic properties and act as an enhancement to the process (Mukherjee et al., 1972 Bockrath and Schroeder, 1981). 

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