Solvent-Free Liquefaction of Brown and Subbituminous Coals Using NiMo Sulfide Catalyst Supported on Carbon Nanoparticles

Abstract

Single- and two-stage liquefaction processes of Yallourn (YLC), South Banko (SBC), and Tanitoharum (THC) coals were performed in an autoclave of 50-mL capacity at variable solvent (tetralin)/coal ratios from 0 to 1.5 under the reaction hydrogen pressure of 15 MPa, using NiMo sulfide supported on carbon nanoparticles or commercial NiMo/alumina and synthetic pyrite catalysts. Although the oil yield decreased very much with all the catalysts by reducing the amount of solvent to zero, the NiMo/carbon catalyst gave much higher oil yields of 52 and 64%, respectively, in the single-stage (450 °C, 60 min) and two-stage (360 °C, 60 min; 450 °C, 60 min) liquefaction under the solvent-free conditions compared with the yield of around 40% by the other two catalysts in both single- and two-stage liquefaction under the same conditions. The oil yield depended on the coal species under the solvent-free conditions, being in the order of SBC > YLC > THC regardless of the reaction conditions. SBC provided the highest oil yields of 60 and 68% in the single- and two-stage liquefaction, respectively, reflecting its higher reactivity and lower gas yield. THC gave the lowest oil yields among the coals examined, although the oil yield reached 60% by the two-stage liquefaction even under the solvent-free conditions. The oil produced with NiMo/carbon catalyst carried lighter fractions in the boiling range 100−300 °C than those with the other catalysts regardless of the reaction conditions and coal species. Such excellent performance of the NiMo/carbon catalyst reflects its higher hydrogenation activity as well as the high dispersion on the coal surface at the initial stage of coal liquefaction, suppressing the retrogressive reactions. It is confirmed that the major portion of solid coal was solubilized during the heating and the initial stage to work as the self-producing solvent under the solvent-free reaction conditions. The design of coal liquefaction with the least use of solvent is discussed for the higher productivity.

Recent Advances in Direct Coal Liquefaction

“…Interestingly, it was found that the use of a non-donor solvent of anthracene or creosote oils in the presence of Mo catalyst precursors led to a higher liquefaction conversion than that of the donor solvent of tetralin [24]. More interestingly, it was demonstrated by many studies [25][26][27] that water could be an effective co-solvent for coal liquefaction by promoting catalyst dispersion.…”

Catalytic Activity of FeMoNi Ternary Sulfide Supported on a Nanoparticulate Carbon in the Liquefaction of Indonesian Coals

“…Fe, Ni, and Mo salts were impregnated onto KB by several impregnating methods using iron(II) fumarate (FeC 4 H 2 O 4 ), Ni(NO 3 ) 2 , or nickel acetate (Ni(OAc) 2 ) and MoO 2 -acetylacetonate (AA) or (NH 4 ) 6 Mo 7 O 24 in methanol or water depending on the solubility of the salts. [9][10][11] The catalysts prepared in the present study are listed Then, the solid in the slurry was recovered by evaporation and dried at 120 °C for 12 h in vacuo. In the case of successive impregnation, nickel was first impregnated followed by iron.…”

“…Other combinations of metal precursors, Mo/Ni, Fe/Mo, and Fe/Mo/Ni were also impregnated on KB in the same manner. [7][8][9][10][11][12][13][14][15] The elemental analyses of Indonesian sub-bituminous coals used, namely, Tanito Harum, Adaro, and South Banko coals, are summarized in Table 4. Commercially guaranteed grade tetralin (TL) and 1-methylnaphthalene were used as a liquefaction solvent and a reactant in the hydrogenation, respectively.…”

“…Commercially guaranteed grade tetralin (TL) and 1-methylnaphthalene were used as a liquefaction solvent and a reactant in the hydrogenation, respectively. 9,11,16,17 Liquefaction Procedure. Coal liquefaction was performed in an electromagnetic-driven autoclave of 50 mL capacity.…”

Catalytic Hydroliquefaction of Sapropels

“…The most important direction for improving and enhancing thermoliquefaction of solid organic feedstocks is the use of catalysts that accelerate H 2 formation that, in turn, prevents condensation of the radicals formed during cracking. It was shown that oxides, sulfides, and chlorides of Group VIII, VI, and IV metals are equally as promising as traditional Group VIII metal catalysts [19][20][21][22][23][24][25]. The researchers found that the liquefaction efficiency of brown coal in the presence of molecular H 2 and a catalyst increased in the order Fe < Sn < Zn < Co < Ni.…”