A recycling hydrogen-donating solvent for direct coal liquefaction and preparation method therefor and use thereof

Abstract

The invention provides a recycling hydrogen-donating solvent for direct coal liquefaction and a preparation method therefor and use thereof, the recycling hydrogen-donating solvent provided by the preparation method of the invention can be used for obtaining the recycling hydrogen-donating solvent with good hydrogen-donating capacity through a relatively simple process flow. The preparation method comprises the following steps: 1) carrying out first fractionation on a direct coal liquefaction oil to obtain liquefied medium oil and liquefied heavy oil; 2) feeding the liquefied heavy oil into a first hydrogenation reactor and carrying out a first-stage hydrogenation reaction; 3) feeding the liquefied medium oil and the liquefied heavy oil subjected to the first-stage hydrogenation reaction in the step 2) into a second hydrogenation reactor, and carrying out a second-stage hydrogenation reaction to obtain hydrogenated product oil; 4) performing second fractionation on the hydrogenated product oil to obtain medium-temperature solvent oil and high-temperature solvent oil; and 5) mixing the medium-temperature solvent oil and the high-temperature solvent oil to prepare the recycling hydrogen-donating solvent.

1 . A method for preparing a recycling hydrogen-donating solvent for direct coal liquefaction, wherein it comprises the following steps:
 1) carrying out first fractionation on a direct coal liquefaction oil to obtain a liquefied medium oil and a liquefied heavy oil, wherein the liquefied medium oil is a distillate oil of 220-320° C., and the liquefied heavy oil is a distillate oil of more than 320° C.;   2) feeding the liquefied heavy oil into a first hydrogenation reactor and carrying out a first-stage hydrogenation reaction;   3) feeding the liquefied medium oil and the liquefied heavy oil subjected to the first-stage hydrogenation reaction in step 2) into a second hydrogenation reactor and carrying out a second-stage hydrogenation reaction to obtain a hydrogenated product oil;   4) performing second fractionation on the hydrogenated product oil to obtain a medium-temperature solvent oil and a high-temperature solvent oil, wherein the medium temperature solvent oil is a distillate oil of 220-350° C., and the high temperature solvent oil is a distillate oil of more than 350° C.; and   5) mixing the medium-temperature solvent oil and the high-temperature solvent oil to prepare the recycling hydrogen-donating solvent.   
     
     
         2 . The method for preparing a recycling hydrogen-donating solvent for direct coal liquefaction of  claim 1 , wherein in step 2), the first hydrogenation reactor is a suspended bed hydrogenation reactor; and in step 3), the second hydrogenation reactor is a fixed bed hydrogenation reactor. 
     
     
         3 . The method for preparing a recycling hydrogen-donating solvent for direct coal liquefaction of  claim 2 , wherein in step 2), the first-stage hydrogenation reaction is carried out under conditions of: a reaction temperature I of 350-400° C., a volume space velocity I of 0.5-3 h −1 , a hydrogen to oil volume ratio I of 400-2000:1 (Nm 3 /m 3 );
 in step 3), the second-stage hydrogenation reaction is carried out under conditions of: a reaction temperature II of 320-380° C., a volume space velocity II of 0.5-3 h −1 , a hydrogen to oil volume ratio II of 400-1600:1 (Nm 3 /m 3 ); and 
 the reaction temperature I is higher than the reaction temperature II, the volume space velocity I is not lower than the volume space velocity II, and the hydrogen to oil volume ratio I is not lower than the hydrogen to oil volume ratio II. 
 
     
     
         4 . The method for preparing a recycling hydrogen-donating solvent for direct coal liquefaction of  claim 3 , wherein in step 2), the first-stage hydrogenation reaction is carried out under conditions of: a reaction temperature I of 360-390° C., a volume space velocity I of 0.8-2.5 h −1 , a hydrogen to oil volume ratio I of 500-1200:1 (Nm 3 /m 3 ), and a reaction pressure I of 13-19 MPa;
 in step 3), the second-stage hydrogenation reaction is carried out under conditions of: a reaction temperature II of 340-370° C., a volume space velocity II of 0.8-2 h −1 , a hydrogen to oil volume ratio II of 500-1200:1 (Nm 3 /m 3 ), and a reaction pressure II of 13-19 MPa; and 
 the reaction temperature I is higher than the reaction temperature II, the volume space velocity I is higher than the volume space velocity II, and the hydrogen to oil volume ratio I is higher than the hydrogen to oil volume ratio II. 
 
     
     
         5 . The method for preparing a recycling hydrogen-donating solvent for direct coal liquefaction of  claim 1 , wherein the first-stage hydrogenation reaction is carried out in the presence of a first hydrogenation catalyst, and the second-stage hydrogenation reaction is carried out in the presence of a second hydrogenation catalyst;
 the first hydrogenation catalyst comprises a first support and a first active component;   the second hydrogenation catalyst comprises a second support and a second active component;   the first active component and the second active component are each independently one or more selected from oxides of Group VIB metal elements and oxides of Group VIII metal elements.   
     
     
         6 . The method for preparing a recycling hydrogen-donating solvent for direct coal liquefaction of  claim 5 , wherein in the first hydrogenation catalyst, the first support is contained in a content of 60-90 wt %, and the first active component is contained in a content of 10-40 wt %; and
 in the second hydrogenation catalyst, the second support is contained in a content of 60-90 wt %, and the second active component is contained in a content of 10-40 wt %.   
     
     
         7 . The method for preparing a recycling hydrogen-donating solvent for direct coal liquefaction of  claim 6 , wherein the first active component and the second active component are each independently a combination of oxide(s) of Group VIB metal element(s) and oxide(s) of Group VIII metal element(s). 
     
     
         8 . The method for preparing a recycling hydrogen-donating solvent for direct coal liquefaction of  claim 1 , wherein in step 5), a mass ratio of the medium-temperature solvent oil to the high-temperature solvent oil is 4:1 to 1:3. 
     
     
         9 . A recycling hydrogen-donating solvent, wherein the recycling hydrogen-donating solvent is prepared by the method for preparing a recycling hydrogen-donating solvent for direct coal liquefaction of  claim 1 . 
     
     
         10 . A method for direct coal liquefaction, wherein the recycling hydrogen-donating solvent used in the direct coal liquefaction method is the recycling hydrogen-donating solvent of  claim 9 . 
     
     
         11 . The method for preparing a recycling hydrogen-donating solvent for direct coal liquefaction of  claim 3 , wherein
 in step 2), the first-stage hydrogenation reaction is carried out under a reaction pressure I of 12-20 MPa; and/or   in step 3), the second-stage hydrogenation reaction is carried out under a reaction pressure II of 12-20 MPa; and/or   the volume space velocity I is higher than the volume space velocity II, and the hydrogen to oil volume ratio I is higher than the hydrogen to oil volume ratio II.   
     
     
         12 . The method for preparing a recycling hydrogen-donating solvent for direct coal liquefaction of  claim 5 , wherein
 the Group VIB metal elements are selected from Mo and/or W, and the Group VIII metal elements are selected from Co and/or Ni; and/or   the first support and the second support are each independently one or more selected from alumina, Y-type molecular sieve and β molecular sieve.   
     
     
         13 . The method for preparing a recycling hydrogen-donating solvent for direct coal liquefaction of  claim 7 , wherein
 in the first hydrogenation catalyst, the oxide(s) of Group VIB metal element(s) are contained in a content of 10-35 wt %, and the oxide(s) of Group VIII metal element(s) are contained in a content of 4-10 wt %; and/or   in the second hydrogenation catalyst, the oxide(s) of Group VIB metal element(s) are contained in a content of 10-30 wt %, and the oxide(s) of Group VIII metal element(s) are contained in a content of 1-6 wt %.   
     
     
         14 . The method for preparing a recycling hydrogen-donating solvent for direct coal liquefaction of  claim 8 , wherein in step 5), a mass ratio of the medium-temperature solvent oil to the high-temperature solvent oil is 1:1 to 3.5:1. 
     
     
         15 . The method for preparing a recycling hydrogen-donating solvent for direct coal liquefaction of  claim 8 , wherein in step 5), a mass ratio of the medium-temperature solvent oil to the high-temperature solvent oil is 2.5:1 to 3.5:1.