High-Performance Magnetic Activated Carbon from Solid Waste from Lignin Conversion Processes. 2. Their Use as NiMo Catalyst Supports for Lignin Conversion

Abstract

Lignin conversion processes produce carbon-rich residues [J. Anal. Appl. Pyrolysis2015113713722; Chem. Rev.201011035523599] that can be converted into valuable materials such as magnetic activated carbons (MACs). Such lignin-derived MACs can be further used as functional substrates for hydrotreating NiMo catalysts. In this work, we studied the activity of different NiMo-MACs for the catalytic conversion of lignin in a formic acid/ethanol media (lignin-to-liquid, LtL, process). Two KOH-activated LtL hydrochars from eucalyptus (MACE) and Norwegian spruce (MACS) lignins were used as catalyst supports. In addition, the activity of the resulting NiMo-MACs, namely, C-MACE and C-MACS, was compared with a NiMo catalyst supported on a commercial activated carbon (AC). At reaction conditions of 340 °C and 6 h, the best result was obtained for the NiMo-MACS with a yield of 72.2 wt % of oil and 21.1 wt % of organic solids. At 300 °C and 10 h, both NiMo-MAC catalysts displayed higher hydrodeoxygenation (HDO) activities than their commercial counterpart, yielding considerably higher oil yields. The higher HDO activities are tentatively assigned to the formation of NiFe species on the catalytic surfaces of the NiMo-MAC catalysts. In addition, the magnetism exhibited by the C-MACS made it easy to recover the catalyst. However, a considerable loss of activity was observed upon recycling due to a chemical modification of the catalyst surface.

Sustainable Thermochemical Single-Step Process To Obtain Magnetic Activated Carbons from Chestnut Industrial Wastes

“…Some of these materials have also very good catalytic properties, so they can be used in various industrial processes. 14,20 In the bioscience and medicine area, an important property of MACs is that these materials can be targeted to a desired place using an external magnetic field. 16 The transformation of an activated carbon into magnetic derivatives is being studied using various methods for its preparation: 16,21 chemical precipitation, 22,23 high-temperature treatment, 18,24 or encapsulation.…”

Dual Function Lewis Acid Catalyzed Depolymerization of Industrial Corn Stover Lignin into Stable Monomeric Phenols

“…Hydrodeoxygenation and hydrogenolysis of lignin have been extensively investigated over various metal (Ni, Ru, Pd, Pt, Rh, and Mo) catalysts supported on carbon, NiW − and Ru-based catalysts supported on SiC, Ru , and Pt-based catalysts supported on alumina − and mixed metal oxides, , Ni/X-zeolite, and hydrated cerium­(III) chloride . The production of aromatic monomers from lignin without using externally added hydrogen is appealing considering the high cost and large quantities of hydrogen required in hydrodeoxygenation and hydrogenolysis processes. ,, Base catalyzed lignin depolymerization with NaOH is effective at high temperatures (240–330 °C). , However, the alkaline conditions lead to reactor corrosion, require a neutralization step during product isolation, and create large amounts of aqueous waste. , …”

Tetraalkylammonium Functionalized Hydrochars as Efficient Supports for Palladium Nanocatalysts

“…This commercial material gave quantitative conversions up to three recyclings under the same reaction conditions (50 °C, 30 min and 0.5 mol% catalyst loading), but the conversion decayed to 36 % in the fourth cycle. The efficient recycling capabilities of Pd@HCh‐F in comparison to Pd@HCh‐D and commercial Pd/C (Figure S8) validate the mild functionalization strategy towards the design of robust hydrochar‐supported catalysts which can be of interest for other carbonaceous raw supports …”

“…Overall, the low porosity of HCh‐D and derived hydrochars might help against deleterious diffusion pathways through the catalyst support itself, thus enabling milder reaction conditions than for micro‐ and mesoporous catalytic materials . In contrast to unfunctionalized supports such as Pd@HCh‐D and those reported in the literature, tetraalkylammonium functionalization allows the recyclability of the catalytic material Pd@HCh‐F mainly thanks to the robustness of the support and Pd‐support electrosteric interactions.…”