Importance of volatile AAEM species to char reactivity during volatile–char interactions

Du, Chunlei; Liu, Li; Qiu, Penghua

doi:10.1039/c6ra27485d

Cited by 27 publications

(16 citation statements)

References 42 publications

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“…The formation and distribution of AAEMs (e.g., Ca), together with tar in the pore structure of graphite, reflect the important role of AAEM species in the homogeneous transformation of tar [35]. In addition, during heterogeneous reforming, AAEMs are precipitated together with volatile matter from corn straw, which will adhere/bond to the surface of the char-based catalyst [43] and participate in the heterogeneous reforming reaction of biomass tar. After tar reforming, the graphite surface contains a small amount of O, which is consistent with the result of Raman analysis.…”

Section: Reactivities Of Char-based Catalystsmentioning

confidence: 99%

Evolution of Char Structure During In-Situ Biomass Tar Reforming: Importance of the Coupling Effect Among the Physical-Chemical Structure of Char-Based Catalysts

et al. 2019

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In order to illustrate the importance of a coupling effect in the physical-chemical structure of char-based catalysts on in-situ biomass tar reforming, three typical char-based catalysts (graphite, Zhundong coal char, and sawdust biochar) were studied in the fixed-bed/fluidized-bed reactor. The physical-chemical properties of carbon-based catalysts associated with their catalytic abilities were characterized by inductively coupled plasma-atomic emission spectroscopy (ICP-AES), Raman, X-ray photoelectron spectroscopy (XPS), scanning electron microscope–energy dispersive spectrometer (SEM-EDS) and N2 adsorption. The relationship between the specific reactivity and tar reforming ability of carbon-based catalysts was discussed through a micro fluidized bed reaction analyzer (MFBRA–MR). The results indicate that the char-based catalyst has a certain removal ability for in-situ biomass tar of corn straw in an inert atmosphere, which is as follows: sawdust biochar > Zhundong (ZD) coal char > graphite. During the in-situ tar reforming, the alkali and alkaline earth metal species (AAEMs) act as adsorption/reaction sites, affecting the evolution of the aromatic ring structure and oxygen-containing functional groups of the char-based catalyst, and also its pore structure. AAEM species on the surface of char-based catalysts are the active sites for tar reforming, which promotes the increase of active intermediates (C-O bond and C-O-AAEMs), and enhances the interactions between char-based catalysts and biomass tar. The abundant AAEMs may lead to the conversion of O=C–O and C=O to C–O. For tar reforming, the internal pore structure of char-based catalysts is little changed, mainly with the carbon deposit forming on the surface pore structure. The carbon deposit from the reformation of straw tar on the char surface has better reactivity than the inherent carbon structure of ZD coal char and sawdust biochar. There is a positive relationship between the MFBRA–MR specific reactivity and tar catalytic reforming ability of char-based catalysts (decided by the coupling effect in their physical-chemical structure), which can be used to determine the catalytic ability of char-based catalysts on tar reforming directly.

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Section: Reactivities Of Char-based Catalystsmentioning

confidence: 99%

Evolution of Char Structure During In-Situ Biomass Tar Reforming: Importance of the Coupling Effect Among the Physical-Chemical Structure of Char-Based Catalysts

et al. 2019

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“…Samples taken the following tar reforming in (A) Ar over pyrolysis biochar, (B) Ar over H 2 O-activated biochar, and (C) Ar over CO 2activated biochar showed that the H 2 O/CO 2 activation of biochar played an important role in maintaining the biochar's active sites, such as surface O-containing functional groups and AAEM species (especially K and Ca) and improved its tar-reforming performance. According to Du et al [67], XPS revealed the evolution of AAEM species and char structures, and concentrations of AAEM species agreed well with surface atomic O concentrations. Similar results were obtained in Figure 10, where Ar reforming over H 2 O-activated biochar yielded a biochar with a higher surface content of O (16.25 atomic%), K (0.80 atomic%), and Ca (0.45 atomic%) than the samples from Ar reforming with the CO 2 -activated biochar and the pyrolysis biochar.…”

Section: Xps Analysis Of Biochar During Biomass Tar Reformingmentioning

confidence: 74%

Mechanism of In-Situ Catalytic Cracking of Biomass Tar over Biochar with Multiple Active Sites

Feng¹,

Zhao²,

Sun³

2020

Applications of Biochar for Environmental Safety

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Biomass tar is the bottleneck in the development of efficient utilization of biomass syngas. The in-situ catalytic cracking biomass tar with multi-active biochar is investigated in a two-stage fluidized bed-fixed bed reactor. It indicates that adding H 2 O or CO 2 is found to improve the homogeneous and heterogeneous cracking of biomass tar. Activation of biochar by H 2 O or CO 2 impacted the morphology of biochar surface and distribution of metal species. H 2 O or CO 2 affects the creation and regeneration of pore structures, influencing the biochar structure and dynamical distribution of alkali and alkaline earth metal species (AAEMs), which ensure enough surface active sites to maintain the catalytic activity of biochar. The tar cracking into low-quality tar or small-molecule gas may be catalyzed by K, while the combination of tar with biochar would be promoted by Ca. The volatilizations of K and Ca, due to their reaction with volatiles, are to a large extent in accordance with their valences and boiling points. The subsequent transformation from the small aromatic ring systems to the larger ones occurs due to the volatile-biochar interaction. During tar cracking over biochar, K and Ca act as the active sites on biochar surface to promote the increase of active intermediates (C▬O bonds and C▬O▬K/Ca).

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“…The formation and distribution of AAEMs (e.g., Ca), together with tar in the pore structure of graphite, reflect the important role of AAEM species in the homogeneous transformation of tar [35]. In addition, during heterogeneous reforming, AAEMs are precipitated together with volatile matter from corn straw, which will adhere/bond to the surface of the char-based catalyst [43] and www.videleaf.com participate in the heterogeneous reforming reaction of biomass tar. After tar reforming, the graphite surface contains a small amount of O, which is consistent with the result of Raman analysis.…”

Section: Physical Structures Of Char-based Catalystsmentioning

confidence: 99%

Evolution of Char Structure During In-Situ Biomass Tar Reforming: Importance of the Coupling Effect Among the Physical-Chemical Structure of Char-Based Catalysts

Feng¹,

Zhao²,

Sun³

2020

Prime Archives in Chemistry

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Importance of volatile AAEM species to char reactivity during volatile–char interactions

Abstract: Behaviour characteristics of volatile AAEM species during volatile–char interactions is important to promote char reactivity.

Cited by 27 publications

References 42 publications

Evolution of Char Structure During In-Situ Biomass Tar Reforming: Importance of the Coupling Effect Among the Physical-Chemical Structure of Char-Based Catalysts

Evolution of Char Structure During In-Situ Biomass Tar Reforming: Importance of the Coupling Effect Among the Physical-Chemical Structure of Char-Based Catalysts

Mechanism of In-Situ Catalytic Cracking of Biomass Tar over Biochar with Multiple Active Sites

Evolution of Char Structure During In-Situ Biomass Tar Reforming: Importance of the Coupling Effect Among the Physical-Chemical Structure of Char-Based Catalysts

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