The catalytic cracking of shale oil-derived vacuum gas oils was explored following a DCC-oriented approach, aiming to produce petrochemical olefins. Two vacuum gas oils from Argentinian shale oils (VGONC1 and VGONC2) and one from a conventional extraction crude oil ("Escalante", VGOC) were converted over a gasoline type equilibrium FCC catalyst in a fluidized bed CREC Riser Simulator reactor (reaction times: 5-45 s, temperatures: 550 degrees C (FCC typical) and 600 degrees C (DCC approximation), cat-to-oil: 5). The raw crude oils exhibited markedly different properties but the resulting VGOs showed very similar distillation curves, shale oil-derived VGOs displaying higher API gravity and significantly lower sulfur content. Conversions were higher at 600 degrees C, but at a given temperature all the feedstocks exhibited similar conversion behavior, product distributions and coke yields. Increasing reaction temperature favored dry gas and light olefin production, while gasoline yields decreased due to overcracking, accompanied by changes in composition and octane number. Aromaticity in gasoline increased from 37 to 60% and olefinicity in LPG was 20% higher at 600 degrees C. Overall, the results indicate that shale oil-derived VGOs can be safely processed under FCC/DCC conditions, their performances being comparable to conventional VGOs, while offering advantages in sulfur content. The operation under conditions close to those of DCC significantly improved the production of light olefins, which is encouraging in a global scenario characterized by greater demand for petrochemical raw materials and increasing availability of shale oils.

This study reports on the design, construction, and operation of a laboratory-scale biomass gasification reactor, together with the procedures used to define and evaluate key operational and performance variables, including piston velocity, nominal biomass residence time, airflow rate, gas yield, lower heating value, and gasification efficiency. The unit is a moving-bed reactor operating in co-current gas–solid mode and reproducing key features of downdraft-like gasification, allowing the identification of the four main reaction zones: drying, pyrolysis, oxidation, and reduction. The reactor exhibits simple operation and handling and, notably, enables controlled axial displacement of the biomass bed through the reaction zone, allowing the nominal solid residence time in the heated zone to be adjusted through piston motion. In addition, the gasification of Spartina argentinensis was investigated in order to evaluate the functionality of the system and to assess reactor performance under selected operating conditions. At operating temperatures of 800–850 °C and an equivalence ratio of 0.2, gas yields exceeded 60 wt%, gasification efficiencies were above 50%, and the product gas reached heating values close to 1000 kcal Nm−3, indicating a favorable fuel quality of the product gas. These results confirm the potential of the proposed reactor as a useful experimental platform for the investigation of biomass gasification under controlled laboratory conditions.

The valorization of agro-industrial byproducts through pyrolysis represents a sustainable route for generating multifunctional raw materials within the framework of a circular bioeconomy. In this study, rice husk (RH) and sugarcane bagasse (SCB) were pyrolyzed in a semi-continuous reactor at 500 degrees C in order to compare product yields and to characterize resulting gas, aqueous and tar fractions. SCB produced the highest bio-oil yield (44.2 wt%), whereas RH generated the highest char yield (42.9 wt%), consistent with its higher ash and lignin contents. In both cases, tar represented about 12 wt% of the bio-oil. Detailed characterization revealed that the liquid products contained oxygenated compounds of interest, mainly carboxylic acids, ketones, and phenols. Acetic acid was the predominant compound in the aqueous phases, while tars were composed mainly of phenols, ketones, furans, and acids. Particularly, phenols accounted for 52.6% and 37.8% of the total chromatographic area in RH and SCB tars, respectively, whereas ketones represented about 10% in both cases. These results show that pyrolysis of agro-industrial residues not only enables energy recovery but also provides liquid fractions enriched in value-added chemicals.

Model oxygenated compounds of bio-oils (ethyl acetate, acetic acid, furfural, and methylcyclopentenolone) and a hydrogen donor hydrocarbon (tetralin) were used to study the hydrogen transfer reactions between hydrocarbons and oxygenated compounds when co-fed in the fluid catalytic cracking (FCC) process. The conversion experiments of pure compounds and their mixtures were carried out in a CREC Riser Simulator fluidized bed laboratory reactor at 500 degrees C over a commercial equilibrium FCC catalyst, reaction times being from 3 to 12 s with a catalyst/oil ratio of 3. Model compounds were reacted individually and taking part of mixtures with tetralin, each of them with a concentration of 5 wt %, using benzene as an inert solvent. The conversion profiles of the reactants and the corresponding product distributions showed that oxygenated compounds compete strongly with the hydrocarbons for the acid sites available on the catalyst surface. The oxygenated compounds convert similarly when reacted pure or in coprocessing, while tetralin decreased its conversion when coprocessed. Hydrogen provided by tetralin is transferred to the oxygenated compounds in coprocessing by means of hydrogen transfer reactions, as shown by changes in product distributions. The index S HT was defined to quantify the magnitude of hydrogen transfer, which increased as a function of reaction time in coprocessing.

The pyrolysis of three different biomasses, rice husk (RH), zoita wood sawdust (ZW) and pine wood sawdust (PW), was studied at 500 °C in a multipurpose unit at the bench scale to determine the yields of the different products and the compositions and properties of the liquid products, with particular emphasis given to the alquitranous fractions (tars). It was possible to link the characteristics of the tars with the compositions of the raw biomasses and verify their potential in various applications. The analytical techniques employed in the characterization of biomasses included lignin, celulose and hemicellulose analysis, ultimate and proximate analysis and thermogravimetry–mass spectrometry analysis (TG-MS). Elemental analysis, gas chromatography–mass spectrometry (GC-MS), nuclear magnetic resonance spectroscopy (1H NMR), Fourier transform infrared spectroscopy (FTIR) and size exclusion chromatography (SEC) were used to characterize the tars. The tar yields were 1.8, 7.4 and 4.0 %wt. in the cases of RH, ZW and PW, respectively. The tars showed higher carbon content, between 60.3 and 62.2 %wt., and lower oxygen content, between 28.8 and 31.6 %wt., than the corresponding raw biomasses. The main components of the tars had aromatic bases, with phenols representing more than 50%. Tar RH included more guaiacols, while Tars ZW and PW included more phenols and alkylated phenols.

Abstract The simultaneous processes of diffusion, adsorption and chemical reaction, considering the transient nature of the concentration profiles in the porous catalyst particles as applied to the analysis of consecutive reactions A → B → C, where reactant and products are subjected to diffusion limitations, are analyzed. The concentrations of the desired intermediate product B, both the average in the catalytic particles and the observed in the fluid phase, initially increase as a function of time until reaching a maximum value and then decline due to the consumption in the secondary reaction. Due to the diffusion restrictions and the adsorption effect, the observed selectivities, calculated from the concentrations in the fluid phase, are always lower than the true selectivities, which also include the amounts accumulated in the particles. Besides depending on the rates of the primary and secondary reactions, the observed yield of product B also depends on the system adsorption capacity, i.e., the relationship between the capacities of the particles and the external fluid phase to accumulate the reactant species. For a given relationship between the intrinsic rates of the primary and secondary reactions, the higher the system adsorption capacity, the lower the observed yield of B as a function of conversion. The relationship between the observed yield of B and the observed conversion of A, calculated considering the transient state of the concentration profiles in the particles, is coincident with that predicted by classical models, which assume the steady state in the particles, when the system adsorption capacity is extremely small.

Malaysia is one of the largest producers of palm oil in the world, which inevitably would also result in huge production of oil palm biomass. Without proper management, this biomass could pose serious environmental problems. Oil palm mesocarp fiber (OPMF) is one type of oil palm biomass which can be processed further for useful application such as dye removal from water. In the present study, OPMF was thermally treated using microwave-assisted pyrolysis. The sample was characterized (proximate, ultimate, lignin content, BET, FTIR, and SEM) and investigated using thermogravimetric analyzer. The activation energy and pre-exponential factor achieved from the Kissinger, Kissinger-Akahira-Sunose (KAS) and Ozawa-Flynn-Wall (OFW) methods were 159.74, 161.90, 163.29 kJ mol-1, and 1.02 x 10-10, 1.90 x 10-13, 3.79 x 10-17 min-1, respectively. The dye removal performance was evaluated using methylene blue (MB) with parameters of initial concentration of MB, contact time, biochar dosage, temperature and pH. The kinetics of MB removal by OPMF was best described using the pseudo-second order kinetic model, followed by Elovich, pseudo-first order and Weber-Morris. As a conclusion, OPMF generated from oil palm processing has the potential to be used as alternative raw materials to produce biochar for dye removal application. image

The analysis of consecutive reactions A→B→C in porous catalyst particles, where the simultaneous processes of diffusion and chemical reactions take place and both reactant and products are subjected to diffusion limitations, was performed for catalyst particles with non-uniform sizes, a fact that has not been considered so far. The system comprises first-order consecutive irreversible reactions that proceed on spherical catalyst particles with a log-normal volume particle size distribution (PSD), which is typical in many catalytic applications. Regardless of the prevailing diffusion regime (chemical control, transition situation or intraparticle diffusion control), the yield of the intermediate product (B) reaches a maximum value as a function of the conversion of reactant (A), then decreases as a consequence of the prevalence of the secondary reaction that converts it into the secondary product (C). If intraparticle diffusion resistances affect the reactant species, given the relationship between the kinetic constants and the mean particle size, the selectivity to the intermediate product is negatively affected by the dispersion in PSD. The larger the dispersion in PSD, the stronger the negative impact.

This work focused on the valorization of tar derived from rice husk pyrolysis as a precursor of matrices for the encapsulation of active principles. In this regard, the development of novel films based on alginate and eugenol-loaded tar microparticles with suitable mechanical properties and antibacterial activity was studied. Tar microparticles loaded with eugenol were incorporated into sodium alginate films and the effect on the mechanical, thermal and humidity resistance properties were determined, as well as the antimicrobial activity. Films with different crosslinking degrees were also prepared using CaCl2, and the eugenol controlled release profiles were evaluated. Crosslinked films exhibited improved mechanical and humidity resistance properties, as well as a lower release rate of eugenol in water. The antimicrobial studies showed that eugenol-loaded films present a higher antimicrobial activity against Staphylococcus aureus. Alginate/eugenol-loaded tar microparticles composites showed an enhancement of antibacterial properties and suitable physical characteristics to be used in active packaging applications.

The valorization of post-consumer waste plastic in a refinery is an attractive initiative to avoid environmental problems caused by the poor plastic waste management. The modification of a bifunctional PtPd/HY catalyst through desilication (using NaOH) of the ultrastable HY zeolite has been carried out to upgrade waste plastic (high-density polyethylene (HDPE)) dissolved in a secondary refinery stream (vacuum gas oil (VGO)) through hydrocracking. Three different catalysts have been studied: the parent (Cat-A), undergoing a desilication cycle (Cat-B), and subjected to two cycles of desilication (Cat-C). The characterization techniques employed have been: N2 adsorption-desorption, TEM, ICP-AES, tert-butylamine-TPD, pyridine FTIR, WDXRF, XRD and TPO. The hy-drocracking tests have been carried out in a semi-batch reactor at: 440 C; 80 bar; catalyst to feed ratio, 0.1 g(cat) (g(feed))(-1); HDPE to feed ratio, 0.2 gHDPE (g(feed))(-1); and reaction time, 2 h. The products have been fractioned ac-cording to their boiling point range in: gas, naphtha, light cycle oil, heavy cycle oil and coke. The composition of each fraction has been determined in terms of concentration of paraffins, olefins, naphthenes and (mono-, di-and poly-) aromatics. The results show that alkaline treated catalysts enhance the fuel production, with high HDPE and HCO conversions. The Cat-C (the one submitted to two desilication cycles) has displayed the greatest per-formance, reducing by half the gas yield and increasing the naphtha yield by 51 wt% respect to those obtained with the parent catalyst (Cat-A). Moreover, it has decreased the coke deposition and the coke formed has been less developed.

The effect on the energy balance of a FCC unit after co-feeding the aqueous fraction of a bio-oil together with a vacuum gas oil (VGO) has been studied. The simulation program considers the interdependency relationship between the reaction and regeneration sections in the unit, where the heat of coke combustion has to sustain the energy requirements to preheat and vaporize the feedstock as well as the endothermic cracking reactions. The combustion of coke deposited on an equilibrium commercial FCC catalyst in cracking various bio-oil/VGO mixtures at 530 degrees C, with catalyst to oil relationships between 3 and 6 in a CREC Riser Simulator laboratory reactor, was investigated by means of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Results showed that the heat from coke combustion is not enough to provide the energy needed in the unit when the amount of bio-oil in the feedstock is larger than 5 wt%, mainly due to the high content of water in the aqueous fraction of the bio-oil and to the lower heat of combustion of the coke formed in co-processing, as compared to the VGO alone.

A vacuum gas oil from an Argentinian shale oil (VGO(NC)), another from a conventional extraction crude oil (VGO(C)) and their 50:50 (mass basis) mixture were converted over two equilibrium, octane-barrel and resid types, catalysts in a fluidized bed CREC Riser Simulator reactor (reaction time: 5-30 s, temperature: 550 ?C, cat-to-oil: 5). The conversions and yields of gases ranked VGO(NC) > mixture asymptotic to VGO(C) over both catalysts. The higher conversions of VGO(NC) are attributed to its paraffinic character, the conversions of the mixture being closer to those of VGO(C) and not the average of the individual conversions of each VGO due to the larger contribution of aromatics, resins, and asphaltenes from VGO(C) to the mixture. These compounds, with marked basic character, adsorb more strongly than paraffins, which are predominant in VGO(NC), thus inhibiting their conversion when present in the mixture. VGO(NC) yielded selectively less gasoline, with lower fuel quality, in consistency with its composition. The yield and fuel quality of gasoline obtained from the mixture was intermediate between those of the individual VGO. Coke yields followed the order VGO(C) asymptotic to mixture > VGO(NC) due to the lower content of coke precursors and CCR of VGO(NC).

Bio-oils are the liquid products from the pyrolysis of biomass, which captured pronounced attention and showed relevance as an alternative source of fuels and chemicals. Bio-oils are complex mixtures of a large number of components, mostly oxygenated compounds, including many different chemical functionalities, which require upgrading (removal of oxygen) to be useful as fuels. As acid or bifunctional metal/acid catalysts are used in upgrading, the components in the mixture will be subjected to many different chemical reactions, including, among others, decarboxylation, decarbonylation, dehydration, demethoxylation, hydrogenation, dehydrogenation, cracking, isomerization, and hydrogen transfer. Purely thermal reactions are also to be produced in upgrading processes. Thus, the set of chemical reactions is exceptionally intricate. This review provides broad information about the mechanisms of numerous reactions which can take place, based on a transversal view, that is, the emphasis is posed on the reactions and the corresponding descriptions embrace the different chemical groups.

The immediate catalytic conversions of pyrolytic bio-oils from pine sawdust and soybean shell over mesoporous catalysts (silica, alumina, and silica-alumina) and their combinations with Y zeolite, were studied. The effect of mesoporosity and acidity on the bio-oil deoxygenation and conversion into hydrocarbons was investigated. Pyrolysis and immediate catalytic conversion of bio-oil were performed in an integrated pyrolysis–upgrading reactor, for 7 min under a 30-ml/min flow of nitrogen at 550 °C. Important differences were observed in the conversion of the bio-oils, according to the composition of the raw biomasses. Pine sawdust bio-oil produced more coke and less hydrocarbons in the range of gasoline than soybean shell bio-oil over all the catalysts. Mesoporous catalysts showed conversion and deoxygenation between 14 and 29 percentage points higher with the more acidic solid (SiO2-Al2O3) in the case of pine sawdust bio-oil and between 2 and 10 percentage points higher with the solid having the highest specific surface area (SiO2) in the case of soybean shell bio-oil. Among the compound catalysts, the best performance for the case of pine sawdust corresponded to the catalyst with the highest mesoporosity (Y/SiO2), while for soybean shell corresponded to the most acidic catalysts (Y/Al2O3 and Y/SiO2-Al2O3). Soybean shell bio-oil showed more low molecular weight compounds (less than 130 g mol−1), which diffuse more easily in the zeolite channels, thus favoring conversion and deoxygenation mechanisms. On the contrary, for pine sawdust bio-oil, the surface area contributed by the mesopores in the matrix played a key role in pre-cracking bulky molecules.

The analysis of the effectiveness factor in catalytic particles with non-uniform size, was performed. The procedure proposed by Weisz and Prater to determine the intrinsic kinetic constants from experimental results was extended to cases where the catalyst particle size distribution is considered. The approach was applied to the study of reactions with power law and Langmuir-Hinshelwood-Hougen-Watson type kinetics, the catalyst particles being spheres with volume log-normal size distribution (typical in, e.g., fluid catalytic cracking catalysts). If the catalytic effectiveness factor is calculated assuming uniform particle size Rm (Rm being the volume to area mean radius), it will be always higher than the actual effectiveness factor. If the particle size distribution is not taken into account during the assessment of the intrinsic kinetic constants by means of the Weisz and Prater method, the values of those constants will be erroneous. The higher the dispersion in the particles size distribution, the higher the error in ignoring the impact of the different sizes.

Two equilibrium FCC catalysts of the octane-barrel (ECAT-D) and resid (ECAT-R) types were used in the cracking of a typical vacuum gasoil (VGO) and its saturated (SF), aromatic (AF), and resin (RF) fractions. The experiments were carried out in a batch, fluidized bed laboratory CREC Riser Simulator reactor. The reaction temperature was 500 degrees C, the catalyst-to-oil relationship was 1, with 0.2 g of the catalyst being used in each experiment, and the reaction times were 0.7, 1.5, and 3 s. The ranking of the reactivities of the different feedstocks was SF > VGO > AF > RF over both catalysts. While the AF and RF fractions yielded more gasoline than the SF fraction, the latter showed the highest yields of LPG. The coke forming trend followed the order SF < VGO < AF < RF. Even though catalyst ECAT-D, with a higher and stronger acidity, was more active than catalyst ECAT-R, which has less acidity and better textural properties (higher mesoporosity and pore diameter), the latter was less affected by coke deposition, considering the changes in the specific surface area and acidic properties after use. Coke impacted more severely on Bronsted acid sites than on Lewis sites, particularly when the AF and RF fractions were used. The stronger acid sites were more severely affected by coke, particularly in catalyst ECAT-D. The negative effect on strong acidic sites was consistent with the increasing basic character of the feedstocks, following the order SF < VGO < AF<RF.

Changes were produced by means of alkaline lixiviation in the porosity of an equilibrium commercial FCC catalyst formulated to maximize the yield of middle distillates, in order to improve its performance in the conversion of tar from the pyrolysis of cow manure into hydrocarbons. The pyrolysis was produced at 650 °C in a fixed bed reactor and the tar was catalytically upgraded, comparing the performances of the parent and modified catalysts under realistic FCC conditions, in a CREC Riser Simulator reactor at 550 °C during 10 s, catalyst to reactant relationships being 3, 5 and 8. The alkaline treatment increased both acidity and average mesopore size of the commercial catalyst, thus favoring the diffusion process of the bulkiest oxygenated molecules in tar. The modified catalyst was more effective in deoxygenating tar (conversions up to 87.5% and deoxygenation up to 74.6%), producing more hydrocarbons and coke than the parent catalyst. According to the chemical nature of the pyrolitic tar from cow manure, a high proportion of paraffins derived from the primary cracking of its components were observed among the product hydrocarbons in the gasoline range over both catalysts.

Disposing livestock wastes from concentrated animal feeding operations represents a problem from both economic and environmental care views, but it is possible to process them in thermochemical processes. The pyrolysis of cow manure was studied, with emphasis on the characterization of products. When the pyrolysis temperature increased from 550°C to 650°C, hydrocarbons yields increased 33% and char yields decreased 90%. Tar (the liquid product with the highest energy density) yields increased from 22 to 35 wt.%, and biooil (the product containing the highest amount of chemical compounds) yields were constant at about 27 wt.%. The biooil contained mainly acids, ketones, and furans, typical in the pyrolysis of cellulose, hemicellulose, and lignin, while the tar contained mainly alcohols and long-chain esters, derived from depolymerization and cracking of lipids and proteins. In comparison with other raw biomasses more extensively studied, cow manure produced much more tar, which could be important in, for example, bioasphalt formulations.

A commercial equilibrium FCC catalyst of the octane-barrel type was subjected to lixiviation treatments with both acidic (HNO3) and basic (NaOH) solutions in order to modify its textural and acidic properties. The alkaline lixiviation doubled the mesopore volume in the commercial catalyst, while the acidic treatment increased the concentration of crystalline component in the catalyst. The catalytic performances of the parent and modified catalysts in the immediate conversion of vapors from pine sawdust fast pyrolysis were evaluated in a fixed bed reactor at 550 degrees C using mass catalyst to bio-oil and tar ratios from 3 to 8. The modified catalysts both produced more hydrocarbons and less coke than the parent commercial catalyst. In turn, comparing the modified samples, the one subjected to alkali treatment was more effective in deoxygenating the pyrolysis vapors, resulting in higher hydrocarbon yields (up to 13.2%) and lower coke yields than the acid modified catalyst, a fact assigned to the higher mesoporosity which improves the diffusion transport of bulky coke precursor molecules. The acid modified catalyst allowed a higher extension of the reaction pathway, the selectivity to aromatic hydrocarbon products being much higher (up to 95.5% of hydrocarbons in the gasoline boiling range). (C) 2018 Published by Elsevier Ltd.

Oxygenated model compounds representing typical components of bio-oils and a hydrocarbon hydrogen donor agent were used to study hydrogen transfer reactions between hydrocarbons and oxygenated compounds when coprocessed over acidic commercial fluid catalytic cracking (FCC) catalysts. Phenol, syringol, and trimethoxybenzene were each mixed with tetralin at 5 wt % individually in benzene as an inert solvent. The mixtures were reacted in a fluidized bed, batch CREC Riser Simulator laboratory reactor during 10 s contact time with a catalyst to oil relationship of 3 at 500 C degrees over a commercial equilibrium FCC catalyst, conditions being selected in order to simulate FCC bio-oil-vacuum gas oil coprocessing. Tetralin was also reacted alone at 5 wt % in benzene to gather background information. When tetralin was the only reactant, its conversion was 87%, the most important reactions being hydrogen transfer, as shown by the yield of naphthalene, and cracking. Alkylation and disproportionation were also observed to a lower extent. In the experiments with the mixtures, the oxygenated compounds converted completely and tetralin converted to less than half the conversion when pure. In these experiments, as compared to pure tetralin, the yield of gases and C-11+ hydrocarbons increased and the yield of coke decreased, showing the interaction between the hydrocarbon and the model oxygenated compound reactants. The index S-HT, which shows the selectivity to hydrogen transfer reactions from tetralin, increased significantly, to about 2 times, in the experiments with the mixtures. Moreover, coke from pure tetralin was shown to be qualitatively different from that in the experiments with the mixtures, where it was more condensed, thus confirming that the reaction pathways are dissimilar.