Feedstock coal liquid

Of the many factors which influence product yields in a fluid catalytic cracker, the feed stock quality and the catalyst composition are of particular interest as they can be controlled only to a limited extent by the refiner. In the past decade there has been a trend towards using heavier feedstocks in the FCC-unit. This trend is expected to continue in the foreseeable future. It is therefore important to study how molecular types, characteristic not only of heavy petroleum oil but also of e.g. coal liquid, shale oil and biomass oil, respond to cracking over catalysts of different compositions. 

The plant will process 27,836 TPSD of Illinois No. 6 high sulfur bituminous coal containing 4.45 wt% sulfur on an as recieved basis. The output of fuel products form the plant is 15,531 BPSD of naphtha and 51,325 BPSD of syncrude. 1,178 tons per day of elemental sulfur is produced. This represents 95 wt% of the total input sulfur in the feedstock coal. Most of the remaining sulfur is still present in the liquid synthetic crude oil. From the available data for this proposed plant, the output of elemental sulfur is calculated to be 0.0176 tons per product barrel. Since a high sulfur coal was used this represents a high sulfur production case as it is likely that direct liquefaction facilities will use high sulfur Eastern bituminous coals as feedstock. 

Proof of the existence of benzene in the light oil derived from coal tar (8) first established coal tar and coal as chemical raw materials (see Feedstocks, coal chemicals). Soon thereafter the separation of coal-tar light oil into substantially pure fractions produced a number of the aromatic components now known to be present in significant quantities in petroleum-derived liquid fuels. Indeed, these separation procedures were for the recovery of benzene—toluene—xylene (BTX) and related substances, ie, benzol or motor benzol, from coke-oven operations (8) (see BTX PROCESSING). 

There is an inherent economic penalty associated with producing liquids from either natural gas or solid coal feedstock. Synthetic liquid fuels technologies are generally not economically competitive with cmde oil processing in the absence of extraneous influences such as price supports or regulations. 

Although the first major use of coal liquids will be as boiler fuels, it is clear that in order to make the largest impact on the U.S. liquid fuel demand, products from direct liquefaction have to be upgraded to quality liquid fuels for both transportation and home heating oil uses. The products coming from the all-distillate coal liquefaction processes such as H-Coal Syncrude, SRC-II and Donor Solvent, along with shale oil production will be candidates for use as refinery feedstock. 

Similar reactions are the hydrogenation of lubricating oils, whereby oils with a flatter viscosity-temperature curve are produced, as well as low-temperature hydrogenation of brown-coal tar, which became known as the TTH process. Although in these two processes the bulk of the feedstock remains liquid and reacts as liquid with hydrogen on the fixed-bed catalyst, the path of the reaction is the same as in the vapor-phase operation. 

The medium-speed diesel (railroad locomotive, marine engines) appears to be another potential application for SRC-II coal liquids to displace petroleum fuels. Other applications being studied by potential users include the automotive turbine, reheat furnace fuel in the steel industry and reformer feedstock for fuel cells. All in all, the products to be derived from coal liquefaction processes like SRC-II can, over time, displace a portion of our requirements for imported petroleum in a variety of end uses. 

The FTS converts synthesis gas into mostly liquid hydrocarbons [12-15]. Depending on the origin of the synthesis gas, the overall process from carbon feedstock to liquid product is called gas-to-liquids (GTL), coal to liquids (CTL), or biomass to liquids (BTL). The product spectrum, however, is broader than liquid hydrocarbons alone and can include methane and alkanes, C H2 +2 (with n from 1 — 100), alkenes or olefins (C H2 n > 2), and to a lesser extent, oxygenated products such as alcohols. Hence the FTS offers the opportunity to convert gas, coal, or biomass-derived syngas into transportation fuels, such as gasoline, jet fuel, and diesel oil, and chemicals, such as olefins, naphtha, and waxes. The reactions need a catalyst, which in commercial applications is either based on cobalt or iron. 

The source of hydrogen for coal liquids production could be, as in the case of shale oil production, either the gas or the bottoms product from the liquids plant. Again, the choice of feedstock for hydrogen production will be dictated by economic, market, and environmental considerations. 

The mercaptans in the feedstock, which was about 56 percent of the total sulfur, was reduced to about six percent at 220°C and then increased to about 36 percent at 300°C and to about 57 percent at 350°C as shown in Table 4. These data confirm the occurrence of mercaptan forming reaction along with HDS of other types of sulfur. Similar results were observed by Sekhar and Rahimi while hydrotreating naphtha derived from coal liquids and heavy oil [12]. Our data show that the maximum temperature of operation for catalyst/4 is 300°C, above which recombination reactions become dominant. 

Hydrotreating of heavier feedstocks including petroleum crude, synthetic crudes, and coal liquids. 

Current concepts for refining the products of coal liquefaction processes rely for the most part on the already existing petrolenm refineries, although it must be recognized that the acidity (i.e., phenol content) of the coal liquids and the potential incompatibility of the coal liquids with conventional petroleum (or even heavy oil) feedstocks may pose severe problems within the refinery system (European Chemical News, 1981). 

Refinery feedstocks from coal (coal liquids) have not been dealt with elsewhere in this text but descriptions are available from other sources (Speight, 2008, 2011). Once the liquids are produced, the next issue is the means by which these liquids can be refined to produce the necessary fuel products. 

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