Lignin is fond of iron! This poster will give an overview of the works conducted at CNRS Nancy on lignin hydrotreatment by iron-based catalysts. Iron/silica and iron/activated carbon were first assessed on guaiacol gas-phase hydrodeoxygenatation [1, 2]. The effect of gas composition was carefully investigated especially for iron speciation by Mossbauer spectroscopy [2]. Iron-based catalyst shows very good selectivity for the production of benzene, toluene or phenol. A kinetic study and a model of the lignin to benzene process have been also developed [3]. The hydrotreatment of real lignin pyrolysis vapours, before any condensation, was then studied [4]. Lignin pyrolysis was conducted in a tubular reactor and vapours were injected in a fixed bed of catalysts (673K, 1 atm) with stacks to investigate the profile of coke deposit. More than 170 GC-analysable compounds were identified by GC*GC (heart cutting)/FID-MS. Lignin oligomers (analysed by petroleomic) were trapped by the catalytic fixed bed and especially by the activated carbon. The catalysts showed a good selectivity for the hydrodeoxygenation (HDO) of real lignin vapours to benzene, toluene, xylenes (BTX), phenol, cresols and alkyl phenols. The spent catalysts were characterised by temperature programmed oxidation (TPO), Transmission Electron Microscopy (TEM) and N2 sorption. Micropores in the Fe/AC catalyst are completely plugged by coke deposit whereas the mesoporous structure of Fe/SiO2 is not affected by coke deposit. TEM reveals two different types of coke deposit: (1) catalytic coke deposited in the vicinity of iron particles and (2) thermal coke (carbonaceous particles of ~ 1µm diameter) formed from the gas-phase growth of lignin oligomers [4]. [1] Applied Catalysis B: Environmental, 115- 116, 63- 73, 2012. [2] Applied Catalysis B: Environmental 129, 528-538, 2013. [3] Energy Fuels 27(2), 975-984, 2013. [4] ChemSusChem, 6 (8) , 1490-1499, 2013.

Aromatic chemicals by iron-catalysed hydrotreatment of lignin pyrolysis vapours

Thermochemical processes such as gasification can decompose carbon feedstocks into gaseous (e.g., syngas), liquid (e.g., oil, tar), and solid (e.g., char) products. Gasification is generally performed in a partial-oxidation environment (e.g., CO2 and steam). In particular, steam gasification has attracted more attention for converting biomass into valuable H2-rich syngas. Biochar is the predominant by-product from biomass pyrolysis or gasification, which has high potential to be used for gas cleaning (e.g., tar removal). This paper reviewed the progress in tar cracking/reforming with biochar catalysts. Biochar can be used as a carbon catalyst or support with fair performance in tar removal. It is noteworthy that biochar catalysts can also be directly gasified to recover energy without the need for frequent regeneration after deactivation. Besides, an integrated strategy of catalytic biomass pyrolysis was proposed to promote the environmentally friendly application of biomass gasification in the future. In general, the high catalytic activity of biochar for tar reforming is attributed to its specific surface properties, amorphous carbon structure with active surface functional groups, and the properties of metal species (e.g., concentration, physicochemical state and dispersion) such as AAEMs in the biochar matrix. Particularly, K-loaded char is significant for tar decomposition in H2O or CO2.

Advances in in situ and ex situ tar reforming with biochar catalysts for clean energy production

High quality H2-rich syngas production from pyrolysis-gasification of biomass and plastic wastes by Ni–Fe@Nanofibers/Porous carbon catalyst

Bimetallic effects in the catalytic hydrogenolysis of lignin and its model compounds on Nickel-Ruthenium catalysts

The gasification of biomass is one of the most prominent technologies for the conversion of the raw material feedstock to polymers, useful chemical substances, and energy. The main engineering challenge during the processing of wastes is the presence of tars in gaseous reaction products, which could make this operation methodology unsuccessfully due to the blockage of separating particle filters, fuel line flow, and substantial transfer losses. Catalytic hydrocarbon cracking appears to be a promising developing approach for their optimal removal. However, it is still highly desirable to enhance the catalysts’ activity kinetics, selectivity, stability, resistance to (ir)reversible coke deposition, and regeneration solutions. The purpose of this Review is to provide a comparative systematic evaluation of the various natural, synthetic, and hybrid ways to convert the model molecular compounds into benzene, toluene, xylene, (poly)aromatics, syngas, and others. The recent scientific progress, including calcite...

https://pubs.acs.org/doi/pdf/10.1021/acs.iecr.9b01219

Catalytic Cracking of Biomass-Derived Hydrocarbon Tars or Model Compounds To Form Biobased Benzene, Toluene, and Xylene Isomer Mixtures

Aiming at the optimization of the dust removal process in the poly-generation system of circulating fluidized bed (CFB) combustion/coal pyrolysis, a granular bed filter (GBF) is applied to the coal pyrolysis by solid heat carrier. By carrying out lab-scale experiments with a moving-bed pyrolyzer, the GBF model proposed by C. Tien et al. was used to describe the dust removal process of the dust-contained volatiles which has high temperature and high viscosity. The model applicability for real pyrolysis volatiles was verified. The results show that, the particle size distribution of the dust uncollected by the GBF is relatively concentrated. The majority particle size of uncollected dust is less than 20 μm, the mass fraction is ∼80%. The GBF is in a state of unsteady operation in the process of dust filtration. With the increase of operating time, the dust is gradually deposited in the GBF, then resulting in an increase of bed pressure drop. In the examined range, the calculational value of GBF efficiency is slightly lower than the experimental value. On the one hand, the filter media particles have a certain specific surface area, so that part of the dust-contained tar can be adsorbed on the filter media surface to achieve a better interception effect. On the other hand, the dust particle deposited in the GBF also plays an important role in dust capture. The C. Tien model results of the initial filtration efficiency can be used as the selection reference of the medium species and the physical properties of the GBF. The higher filter height, slower superficial gas velocity, and smaller size of medium are conducive to decrease the dust content in the pyrolysis products. This study can provide basic data for the dust removal process in the poly-generation system of CFB combustion/coal pyrolysis.

/pdf/studies-of-granular-bed-filter-for-dust-removal-in-the-54x0sc4l1k.pdf

Studies of granular bed filter for dust removal in the process of coal pyrolysis by solid heat carrier

Effect of solvent pretreatment on pyrolysis characteristic of high-sulfur bituminous coal

Natural dolomite catalysts, representing a cheap and environmentally friendly alternative to nickel-based compounds, can be used for the cracking of anthracene oil to form more valuable products. The impact of operating conditions (temperature, water/oil mass ratio, and space velocity) on the distribution and yield of pyrolysis products was investigated in a fixed-bed reactor, providing insights into the mechanism of cracking. The gaseous products were analyzed by gas chromatography; the catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy; and the pyrolysis oil was analyzed by gas chromatography–mass spectrometry. The obtained results revealed that the gaseous products comprised H2, CO, CO2, CH4, and C2+. In comparison to anthracene oil, the pyrolysis oil contained significantly decreased amounts of alkyl aromatic hydrocarbons and indene compounds as well as an increased content of polycyclic aromatic hydrocarbons, such as napht...

Effects of Natural Dolomite Catalysts on Cracking Anthracene Oil

In view of the polygeneration technology of coal pyrolysis/circulating fluidized bed combustion, circulating ash and coal were layered in the pyrolysis reactor to investigate the secondary ...

Secondary Catalytic Reaction of Circulating Ash on the Primary Volatiles of Coal Pyrolysis

To develop tar-cracking catalysts with an industrial application value and to study the effect of dust species on the cracking characteristics of dust-containing tar, four kinds of modified nickel (Ni)-based catalysts were prepared by the incipient wetness impregnation method. Alkali and alkaline earth metal oxides K2O and MgO and transition metal oxides CeO2 and ZrO2 were used as additives. The activities and stability performances of these catalysts were investigated in a fixed-bed apparatus. The additions of K2O and MgO neutralized the acidity of the catalysts and reduced carbon deposition on the catalyst surface, and the additions of CeO2 and ZrO2 improved active ingredient dispersion. X-ray diffraction studies revealed that the (Zr0.85Ce0.15)O2 solid solution has good stability. The 2% NiO/1% CeO2/2% ZrO2–Al2O3 catalyst shows the highest activity and stability among the four modified Ni-based catalysts. Depositions of different species of dust on the catalyst surface have different influences on the ...

Juan Yu

Papers

Studies of granular bed filter for dust removal in the process of coal pyrolysis by solid heat carrier

Effect of solvent pretreatment on pyrolysis characteristic of high-sulfur bituminous coal

Effects of Natural Dolomite Catalysts on Cracking Anthracene Oil

Secondary Catalytic Reaction of Circulating Ash on the Primary Volatiles of Coal Pyrolysis

Effect of Additives on Cracking Characteristics of Dust-Containing Tar over Nickel-Based Catalysts