JPH0410517B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coal liquefaction method, and in particular, a first reaction step in which a solvent and coal are mixed and heated to solubilize the coal, and the first reaction step product is treated with a catalyst and a gaseous state. The present invention relates to an improvement in a two-stage liquefaction method comprising a second stage reaction step of hydrogenation in the presence of hydrogen. In recent years, with the diversification of energy sources, the development of coal liquefaction processes has been accelerated, and numerous studies are being conducted. Among them, the two-stage liquefaction method involves first solubilizing coal under relatively mild conditions using the ability of a solvent, and then using a catalytic action to decompose and lighten the solubilized components in the presence of hydrogen. This is an excellent method because it reduces hydrogen consumption, increases flexibility in product diversification, etc. On the other hand, in the two-stage liquefaction method, since the first stage reaction is controlled by the ability of the solvent, an important issue is how to maintain the properties of the solvent. In the first stage reaction, coal is thermally decomposed under high temperature conditions and converted into polymeric components called preasphaltenes and asphaltenes, which are then solubilized. The radicals generated during this thermal decomposition receive hydrogen from hydrogen-donating solvents and/or hydrogen-rich parts of the coal, and the solvents that are about to easily transfer hydrogen (this phenomenon is called the solvent shuttling effect). ,
Polycyclic aromatics are said to have this effect) and are thought to receive hydrogen from them to stabilize them. Therefore, the solvent supplied to the first stage reaction must be a solvent with excellent functions as described above. If not, the active pre-asphaltenes and asphaltenes generated during thermal decomposition will recombine and cause extremely high decomposition. This results in the conversion to macromolecules that are difficult to digest. As a high-quality solvent that meets the above conditions, the present inventors and other researchers have suggested partially hydrogenated polycyclic aromatic compounds having 2 to 5 rings. Therefore, the success or failure of the two-stage liquefaction method depends on how to rationally produce this solvent within the coal liquefaction process. In order to produce a partially hydrogenated polycyclic aromatic, it is sufficient to hydrogenate the polycyclic aromatic in the presence of a catalyst (for example, a nickel-molybdenum-based catalyst or a cobalt-molybdenum-based catalyst) and gaseous hydrogen. teeth
It is a high-temperature, high-pressure reaction of 300℃ or higher and 100Kg/cm ² G or higher, which requires a high-pressure reactor, a compressor to supply hydrogen under high pressure, a device to collect and circulate surplus hydrogen from the reaction, Various peripheral equipment is required, such as a pump that supplies raw materials under high pressure and a device that separates gas from the reaction solution and reduces the pressure to normal pressure. In addition, since the solvent/coal ratio in the first stage reaction process is 1.5 to 3.0, the amount of solvent handled will be 1.5 to 3.0 times the original amount of coal processed, which will reduce the construction and operating costs of the coal liquefaction plant. It will become a part of the future. Furthermore, a method has also been used in which the solvent component is simultaneously hydrogenated in the second reaction step for decomposing and lightening the solubilized coal in the presence of a catalyst and hydrogen. In this case, the important problem is that the conditions for decomposing and lightening the solubilized material and the conditions for appropriately hydrogenating the effective components of the solvent do not match. In other words, the decomposition and lightening conditions for the solubilized material are more severe than the hydrogenation conditions for the active component of the solvent, so if the conditions are made to mainly decompose, the active component of the solvent will be overhydrogenated, and the solvent capacity will be extremely reduced. If the solvent is mainly hydrogenated, the decomposition rate will be insufficient. The present invention is a new two-stage coal liquefaction method that overcomes the difficulties of the conventional methods described above, and streamlines the decomposition and lightening of coal solubilized materials and the appropriate hydrogenation of the active components of the solvent within the second stage reaction process. It provides a method to do so. That is, the present invention mixes and heats coal and a solvent,
In a coal liquefaction method consisting of a first reaction step for solubilizing coal and a second reaction step for hydrotreating at least a part of the first reaction step product, the first step reaction product is heated to a boiling point. The heavy fraction is separated into an oil component with a boiling point of 400 to 500°C or less and a heavy component with a boiling point higher than that, and the second stage reaction step is configured with a plurality of reaction zones connected in series with substantially equal pressure. The gist is a two-stage coal liquefaction method characterized in that the oil is supplied from the first of a plurality of reaction zones and the oil is supplied from a middle of the plurality of reaction zones. According to the present invention, first, the mixture containing the solvent component produced in the first reaction step is distilled to a boiling point.
Separates into oil component with boiling point below 400-500℃ and heavy component with boiling point above. In this case, the distillation cut temperature should be set so that the active ingredients as a solvent (hydrogenated polycyclic aromatics and non-hydrogenated polycyclic aromatics) are recovered in the oil. The range is preferably 400 to 500°C from the aromatic boiling point of the ring. Next, the second stage reaction step is composed of a plurality of reaction zones connected in series with substantially the same pressure, and the heavy component is supplied from the first reaction zone, while the oil component is supplied from the middle. By feeding the heavy components and oil components separately in this way, the residence time in each reactor can be changed almost arbitrarily, and the above-mentioned lightening of the heavy components and hydrogenation of the solvent can be carried out in a series. The reaction can be carried out using a reactor. As a specific embodiment, reactors such as a fixed bed, a fluidized bed, and a suspended bed may be connected in series, and oil (solvent component) may be supplied from a connection in the middle of the reactors, or one reactor may be connected in series. One example is a method in which a fixed bed reactor is alternately filled with catalyst layers and layers of inert fillers, and oil is supplied from the intermediate catalyst layers. Furthermore, the method of supplying the oil is not limited to the method in which all of the oil is supplied from the middle, and a portion of the oil may be supplied to the first reaction zone together with the heavy components. The present invention will be specifically explained below with reference to Examples. [Comparative Example] Coal-based heavy oil containing a large amount of polycyclic aromatics was treated with a nickel-molybdenum catalyst (1.6φ extrusion product, composition: MoO ₃ 19.8wt). %, NiO3.4wt%, Al ₂ O ₃ 76.8wt
%) of the solvent and coal obtained by hydrotreating the
The coal was maintained at 450° C. and 15 kg/cm ² G for 7 minutes to solubilize the coal. Then, by using a high-temperature centrifuge and distillation operation, a solubilized substance of coal with a solid content of 0.3wt% and a boiling point of 450℃ or higher (hereinafter abbreviated as SC) and a boiling point of 300℃ or higher are used.
The solvent fraction in the range of 450°C was collected and used as the raw material for the hydrogenation test. In the solvent fraction, there are typical 3- and 4-ring polycyclic aromatic compounds (hereinafter abbreviated as PA components) that are recognized as prominent peaks in temperature-programmed gas chromatography.
is 42.9wt%, and their partial hydrides (dihydrides and tetrahydrides, hereinafter abbreviated as HPA components)
It was present at 4.2wt%. Next, a mixture of 1000 g of the above SC and 3300 g of oil was supplied to a fixed bed reactor at a feed rate of 250 g/hr, and a hydrogenation reaction was carried out at 380° C. and 150 Kg/cm ² G. The fixed bed reactor has a No. 1 reactor and a No. 2 reactor connected in series, each of which is filled with 250 ml of the nickel-molybdenum catalyst (same as above). The reaction products were separated by distillation and measured by gas chromatography in the same manner as for the raw materials. The results of this comparative example are shown in Table 1. The change in SC amount was 537 g on the product side compared to 1000 g on the feed side, giving a conversion rate of 46.3%, giving good results. However, it can be seen that the increase in the amount of HPA component is small compared to the large decrease in the amount of PA component, which is not suitable for producing high-quality solvents. [Example] The same fixed bed reactor as in the comparative example was used, using the same SC 1000 g and solvent fraction 3300 g as the test raw materials as in the comparative example. 170g/mixture of 1000g SC and 700g solvent distillate
The reaction products were fed to the No. 1 reactor at a feed rate of 260 g/hr, and 2600 g of the remaining solvent fraction was mixed under pressure with the reaction products at a feed rate of 260 g/hr, and the mixture was fed to the No. 2 reactor. Both reactors No. 1 and No. 2 were filled with 250 ml of a nickel-molybdenum catalyst (same as the comparative example), and the reaction temperature was 380° C. and the pressure was 150 Kg/cm ² G. The reaction product was analyzed in the same manner as in the comparative example, and the results shown in Table 1 were obtained. In this example, the processing speed of all SC solvent fractions is increased compared to the comparative example. In addition, the amount of HPA component increases in response to the decrease in the amount of PA component, and a high-quality solvent is produced. Furthermore, the change in SC amount is also equivalent to that of the comparative example. 【table】

Claims (1)

[Claims] 1. In a coal liquefaction method consisting of a first reaction step in which coal and a solvent are mixed and heated to solubilize the coal, and a second reaction step in which at least a part of the product of the first reaction step is hydrotreated, The product of the first stage reaction process is separated into an oil component with a boiling point of 400 to 500°C or less and a heavy component with a boiling point higher than that, and the second stage reaction process is performed in multiple reaction zones in series with substantially equal pressure. A two-stage liquefaction method for coal, characterized in that the heavy component is supplied from a first of a plurality of reaction zones, and the oil component is supplied from a middle of the plurality of reaction zones.