Ultra-large-scale Synthesis of Fe₃O₄ Nanoparticles and Their Application for Direct Coal Liquefaction

Abstract

Ultra-large-scale synthesis of iron oxide nanoparticles (875 g) has been achieved in a single reaction via a facile solution-based dehydration process. The obtained nanoparticles capped with hydrophobic oleic acid ligands are magnetite with the average size of 5 nm. The synthesized samples exhibit a higher catalytic activity toward the direct coal liquefaction (DCL) than the commercial Fe3O4 powders. The conversion, oil yield, and liquefaction degree with the synthesized Fe3O4 nanoparticles are 89.6, 65.1, and 77.3%, respectively. The excellent catalytic performance of the synthesized Fe3O4 nanoparticles can be attributed to their extremely small size and high dispersity. This facile approach to prepare highly active nanocatalyst for the DCL will be applicable for future industrial processes.

Direct Coal Liquefaction with Fe3O4 Nanocatalysts Prepared by a Simple Solid-State Method

“…Liquefaction reactions were conducted in a 0.5 L batch-stirred autoclave. The process of DCL catalyzed by Fe 3 O 4 nanoparticles and the separation procedure of products were similar to the previous studies [19,20]. In a typical experiment, 10.0 g of coal, 20.0 g of tetralin as a solvent, Fe 3 O 4 nanoparticles (Fe is 1.4 wt % of dry and ash-free (daf) coal) as a catalyst, and sulfur (S/Fe mole ratio is 1.8) as a cocatalyst were mixed and charged into the reactor.…”

“…In particular, nanosized iron-based materials show superior catalytic activity for DCL [17,18]. Recently, Fe 3 O 4 nanoparticles capped with oleic acid have been prepared by our group by thermal decomposition and solution-based dehydration process, respectively [19,20]. The nanocatalysts displayed higher activity toward DCL than commercial Fe 3 O 4 powders.…”

“…The nanocatalysts displayed higher activity toward DCL than commercial Fe 3 O 4 powders. In particular, a large-scale synthesis of Fe 3 O 4 nanoparticles was achieved through the solution-based dehydration method, which is beneficial for practical DCL applications [20]. However, a large volume of organic solvent is involved in this method, which raises the cost, and is potentially harmful to the environment.…”

Roles of Na 2 CO 3 in lignite hydroliquefaction with Fe-based catalyst

“…Moreover, Fe-based catalyst is well-known to be the most practical catalyst for coal hydroliquefaction, because of its relatively high activity, low cost and environmental benign for disposal [5][6][7][8][9][10][11][12][13][14][15][16][17]. Consequently, plenty of studies on coal hydroliquefaction mainly focused on these investigations for Fe-based catalyst: how to improve its catalytic activity by modifying its physical and chemical structures such as crystalline size [6], pore structure [18], dispersive degree [19,20], Fe precursor phase [21], Fe active phase [22], and surface acidity and basicity [8,[23][24][25].…”

Advances in Lignite Extraction and Conversion under Mild Conditions

“…Fe-based catalysts especially iron sulfides are well-known to be the most practical catalysts for coal liquefaction because of their low cost and environmentally benign for disposal [149][150][151][152][153][154]. It is widely believed that Fe 1-x S is an active phase for iron sulfides during coal liquefaction,[155][156][157] but in fact the formation of H .…”