| 摘要 |
#CMT# #/CMT# A method for the hydroconversion of heavy hydrocarbon fractions uses a catalyst obtained by injecting a Group VIB or VIII metal-based precursor into the feed in the absence of an oxide support, heating in presence of hydrogen sulfide to form a dispersed sulfurised catalyst and then adding a special porous alumina support with a polymodal structure consisting of juxtaposed agglomerates and resembling a chestnut fruit. #CMT# : #/CMT# A method for the conversion of heavy hydrocarbon fractions in a slurry reactor in presence of hydrogen and a catalyst composition obtained by (i) injecting a catalyst precursor containing Group VIB and/or VIII metal(s) into the feed in the absence of an oxide support, (ii) heating at up to 400[deg] C in the presence of hydrogen sulfide to form the dispersed sulfurised catalyst, (iii) contacting this catalyst with aluminum oxide particles (I) containing no silica, aluminosilicate, titanium dioxide, zeolite or clay and showing a porous, polymodal structure of many juxtaposed agglomerates in the form of acicular plates, each oriented radially to one another and to the centre of the agglomerate, the particles having an irregular, non-spherical shape and being mostly in the form of fragments obtained by crushing alumina balls, and (iv) introducing the resulting catalyst composition into the reactor. #CMT#USE : #/CMT# For the hydroconversion of heavy hydrocarbon fractions. #CMT#ADVANTAGE : #/CMT# The use of a special catalyst support in the form of porous alumina with a polymodal structure (like a chestnut fruit) enables better performance with regard to de-asphaltage and demetallisation and also with regard to better product stability. #CMT#INORGANIC CHEMISTRY : #/CMT# Preferred Materials: Oxide particles (I) with a loss of 1-15 wt.% on calcination at 1000[deg] C, a BET surface of 75-250 m 2>/g, and a total pore volume (by mercury porosimetry) of 0.5-2.0 cm 3>/g with 0-10% of the pores showing an average diameter of less than 100 Å , 40-80% between 100 and 1000 Å , 5-60% between 1000 and 5000 Å , 3-50% between 5000 and 10000Å and 5-20% larger than 10000 Å . Preferably, more than 20% of the pore volume is in pores with a diameter of more than 1000 Å and the average diameter of such pores is 4000-6000 Å . The catalyst precursor is (a) an organometallic compound which is soluble in the hydrocarbon feed, or (b) a water-soluble compound, preferably a salt or an acid or a heteropolyanion containing molybdenum, nickel and phosphorus or molybdenum, cobalt and phosphorus, preferably based on ammonium heptamolybdate, phosphomolybdic acid, nickel nitrate or nickel acetate. The dispersed catalyst is present in the feed in amounts of 10-1000 ppm (based on elemental metal(s)). The oxide particles (I) are obtained by (a) granulating active alumina powder with a poorly crystallised or amorphous structure to give agglomerates in the form of balls, (b) maturing at 60-100[deg] C in a humid atmosphere and then drying, (c) sieving to obtain the required fraction, (d) crushing this fraction, (e) calcining at 250-900[deg] C, (f) impregnation with acid and hydrothermal treatment at 80-250[deg] C and (g) drying followed by calcination at 500-1100[deg] C. (I) show an average particle size of 10-1000 (preferably 100-800) microns.Preferred Method: The contact stage (iii) involves injecting the particles (I) with the dispersed, sulfurised catalyst. The concentration of (I) in the hydrocarbon feed is 0.1-20 (preferably 0.5-10) wt.%. The slurry reactor is supplied with a feed for which the boiling point is above 540[deg] C for at least 80 wt.% of the feed components with initial boiling points above 300[deg] C, and is operated at a total pressure of 1-50 MPa, a hydrogen partial pressure of 1-50 MPa, a temperature of 300-600[deg] C, and a hydrocarbon dwell time of 5 minutes to 20 hours in the reaction zone. #CMT#EXAMPLE : #/CMT# Alumina obtained by the rapid decomposition of hydrargillite in air at 1000[deg] C was milled to an average particle size (d50) of 7 microns, mixed with 15 wt.% wood flour, pelleted in a granulator, matured for 24 hours at 100[deg] C under water vapor, dried, sieved, crushed and calcined. The resulting balls were impregnated with an aqueous solution of nitric and acetic acids and then autoclaved for 2 hours at 210[deg] C and 20.5 bar, to give crushed agglomerates which were dried for 4 hours at 100[deg] C and calcined for 2 hours at 650[deg] C. These agglomerates (I) showed a d50 of 200-500 microns, a pore volume of 0.95 cm 3>/g and a BET surface of 130 m 2>/g; the pore volume distribution was 0.2% with a d50 smaller than 100Å , 75% between 100 and 1000Å , 12.5% between 1000 and 5000Å , 6% between 5000 and 10000Å , and 6.5% larger than 10000Å . The particles (I) were tested in a slurry reactor in combination with molybdenum octoate in amounts of 300 ppm Mo, using a heavy hydrocarbon feed containing 13 wt.% C7 asphaltenes, 134 ppm nickel and 660 ppm vanadium; reactor conditions were 410[deg] C, 150 bar (hydrogen) and 1.5 hours (residence time). This involved (a) adding the Mo octoate to the feed in presence of dimethyl disulfide (DMDS) under hydrogen at 100 bar, heating for 1 hour at 350[deg] C to decompose the DMDS and form a dispersion of molybdenum disulfide, and (b) cooling to below 100[deg] C, stripping out hydrogen and hydrogen sulfide with nitrogen, adding 2 wt.% oxide (I) and then proceeding with hydroconversion as above. This gave a conversion of 52 (50) %, a hydrodemetallisation of 80 (75) wt.% and a hydro-deasphaltation of 62 (59) wt.%. Values in brackets were obtained by using crushed alumina particles with a bimodal pore distribution but without the special "chestnut fruito structure shown by (I). |
