Ex-situ catalytic upgrading of vapors from fast microwave-assisted co-pyrolysis of Chromolaena odorata and soybean soapstock

Use of activated Chromolaena odorata biomass for the removal of crystal violet from aqueous solution: kinetic, equilibrium, and thermodynamic study

In the present study, biomass from the Chromolaena odorata plant's stem was activated using sulfuric acid to adsorb crystal violet (CV) dye. The adsorption operation of CV dye was studied considering the effect of variables like pH, initial dye concentration, time, adsorbent dosage, and temperature. The pseudo-second-order equation best fitted the kinetic study. The thermodynamic parameters such as activation energy (9.56 kJ/mol), change in Gibbs energy (81.43 to 96.7 kJ/mol), enthalpy change (6.89 kJ/mol), and entropy change (-254.4 J/mol K) were calculated. Response surface methodology estimated that at pH (4.902), adsorbent dosage (8.33 g/L), dye concentration (82.30 ppm), and temperature (300.13 K) dye removal of 97.53% is possible. FTIR, SEM, XRD, BJH, and BET confirmed adsorption operation. The adsorbent can be reused for 3 cycles effectively. Langmuir isotherm which best fitted the adsorption operation was used for designing a theoretical single-stage batch adsorber for large-scale operation.

Catalytic Upgrading of Residual Fat Pyrolysis Vapors over Activated Carbon Pellets into Hydrocarbons-like Fuels in a Two-Stage Reactor: Analysis of Hydrocarbons Composition and Physical-Chemistry Properties

This work investigated the influence of the reaction time and catalyst-to-residual fat ratio by catalytic upgrading from pyrolysis vapors of residual fat at 400 °C and 1.0 atmosphere, on the yields of reaction products, physicochemical properties (density, kinematic viscosity, and acid value) and chemical composition of bio-oils, over a catalyst fixed-bed reactor of activated carbon pellets impregnated with 10.0 M NaOH, in semi-pilot scale. The experiments were carried out at 400 °C and 1.0 atmosphere, using a process schema consisting of a thermal cracking reactor of 2.0 L coupled to a catalyst fixed-bed reactor of 53 mL, without catalyst and using 5.0%, 7.5%, and 10.0% (wt.) activated carbon pellets impregnated with 10.0 M NaOH, in batch mode. Results show yields of bio-oil decreasing with increasing catalyst-to-tallow ratio. The GC-MS of liquid reaction products identified the presence of hydrocarbons (alkanes, alkenes, ring-containing alkanes, ring-containing alkenes, and aromatics) and oxygenates (carboxylic acids, ketones, esters, alcohols, and aldehydes). For all the pyrolysis and catalytic cracking experiments, the hydrocarbon selectivity in bio-oil increases with increasing reaction time, while those of oxygenates decrease, reaching concentrations of hydrocarbons up to 95.35% (area).

A Review of Bio-Oil Production through Microwave-Assisted Pyrolysis

The issue of sustainability is a growing concern and has led to many environmentally friendly chemical productions through a great intensification of the use of biomass conversion processes. Thermal conversion of biomass is one of the most attractive tools currently used, and pyrolytic treatments represent the most flexible approach to biomass conversion. In this scenario, microwave-assisted pyrolysis could be a solid choice for the production of multi-chemical mixtures known as bio-oils. Bio-oils could represent a promising new source of high-value species ranging from bioactive chemicals to green solvents. In this review, we have summarized the most recent developments regarding bio-oil production through microwave-induced pyrolytic degradation of biomasses.

Pyrolysis synergy of municipal solid waste (MSW): A review

The synergistic pyrolysis of municipal solid waste (MSW) were recently explored. This review aims to provide an overview on the synergistic pyrolysis studies of MSW, focusing on the synergy occurred during co-pyrolysis of different constituents of MSW. The interactions of intermediates released during pyrolysis can shift end product distributions, accelerate pyrolysis rates, and preferred production of specific compounds, which were categorized into four basic types with discussions. The pyrolysis synergy is proposed to be the key for success of pyrolytic practice of MSW that can handle the waste with maximal resource recovery and minimal carbon emission.

Slow pyrolysis of municipal solid waste (MSW): A review

In recent years, extensive studies have been carried out to improve our knowledge of the reactor operations and system performance in thermal pyrolysis of municipal solid wastes (MSW). However, the fundamentals of MSW pyrolysis and their engineering applications remain unsatisfactorily explored. This paper is a review of the pyrolysis of MSW and synergistic co-pyrolysis of the constituents of MSW with reference to pyrolytic performance, the distribution and energy content of the end products, and the mechanisms of the synergistic effects. The prospects for, and challenges of, the MSW pyrolysis process are provided. A MSW pyrolytic process with maximal energy recovery and minimal carbon footprint is proposed.

Biomass Pyrolysis Technology by Catalytic Fast Pyrolysis, Catalytic Co-Pyrolysis and Microwave-Assisted Pyrolysis: A Review

With the aggravation of the energy crisis and environmental problems, biomass resource, as a renewable carbon resource, has received great attention. Catalytic fast pyrolysis (CFP) is a promising technology, which can convert solid biomass into high value liquid fuel, bio-char and syngas. Catalyst plays a vital role in the rapid pyrolysis, which can increase the yield and selectivity of aromatics and other products in bio-oil. In this paper, the traditional zeolite catalysts and metal modified zeolite catalysts used in CFP are summarized. The influence of the catalysts on the yield and selectivity of the product obtained from pyrolysis was discussed. The deactivation and regeneration of the catalyst were discussed. Catalytic co-pyrolysis (CCP) and microwave-assisted pyrolysis (MAP) are new technologies developed in traditional pyrolysis technology. CCP improves the problem of hydrogen deficiency in the biomass pyrolysis process and raises the yield and character of pyrolysis products, through the co-feeding of biomass and hydrogen-rich substances. The pyrolysis reactions of biomass and polymers (plastics and waste tires) in CCP were reviewed to obtain the influence of co-pyrolysis on composition and selectivity of pyrolysis products. The catalytic mechanism of the catalyst in CCP and the reaction path of the product are described, which is very important to improve the understanding of co-pyrolysis technology. In addition, the effects of biomass pretreatment, microwave adsorbent, catalyst and other reaction conditions on the pyrolysis products of MAP were reviewed, and the application of MAP in the preparation of high value-added biofuels, activated carbon and syngas was introduced.

Enhanced bioaromatics synthesis via catalytic co-pyrolysis of cellulose and spent coffee ground over microporous HZSM-5 and HY

Catalytic co-pyrolysis (CCP) of spent coffee ground (SCG) and cellulose over HZSM-5 and HY was characterized thermogravimetrically, and a catalytic pyrolysis of two samples was conducted using a tandem micro reactor that directly connected with gas chromatography-mass spectrometry. To access the more fundamental investigations on CCP, the effects of the zeolite pore structure, reaction temperature, in-situ/ex-situ reaction mode, catalyst to feedstock ratio, and the SCG and cellulose mixing ratio were experimentally evaluated. The temperature showing the highest thermal degradation rate of cellulose with SCG slightly delayed due to the interactions during the thermolysis of two samples. HZSM-5 in reference to HY produced more aromatic hydrocarbons from CCP. With respect to the reaction temperature, the formation of aromatic hydrocarbons increased with the pyrolytic temperature. Moreover, the in-situ/ex-situ reaction mode, catalyst/feedstock, and cellulose/SCG ratio were optimized to improve the aromatic hydrocarbon yield.

Microwave-assisted catalytic upgrading of co-pyrolysis vapor using HZSM-5 and MCM-41 for bio-oil production: Co-feeding of soapstock and straw in a downdraft reactor

Microwave-assisted co-pyrolysis of low hydrogen-to-carbon and high hydrogen-to-carbon effective ratio materials with the aid of HZSM-5 and MCM-41 is a promising technique to improve the bio-oil quality. The low content of hydrocarbons and short life cycle of catalyst limit the application of pyrolysis technology in biomass energy conversion. The effects of catalytic temperature, and HZSM-5-to-MCM-41, feedstock-to-catalyst, and straw-to-soapstock ratios on the yield and composition of bio-oil were studied in this work. The quality of bio-oil during biomass pyrolysis can be improved by adjusting the operating conditions. The optimal catalytic temperature, and ratios of HZSM-5-to-MCM-41, feedstock-to-catalyst, and straw-to-soapstock were 400 °C, 1:1, 2:1, and 1:2, respectively. The addition of MCM-41 was beneficial in prolonging the life of HZSM-5 since the macromolecular compounds cracked when MCM-41 was added which restrain the generation of coke. The co-pyrolysis of soapstock with straw advanced the deoxygenation of oxygen-containing compounds especially phenol from straw during pyrolysis.

Fast microwave-assisted pyrolysis of wastes for biofuels production - A review

Microwave-assisted pyrolysis of waste suffers from the problem that the waste generally has low microwave absorptivity thereby resulting in low heating rate and low pyrolysis temperature. In this case, fast microwave-assisted pyrolysis is proposed and developed to help the pyrolysis of waste. This study describes two methods that can be used to realize fast microwave-assisted pyrolysis of waste: (1) premixed method (wastes are mixed with microwave absorbent) and (2) non-premixed method (wastes are poured onto the heated microwave absorbent bed). Then, biofuels (bio-oil, bio-gas, and bio-char) produced from fast microwave-assisted pyrolysis of wastes are reviewed. The review results show that the yields of bio-oil, bio-gas, and bio-char obtained from fast microwave-assisted pyrolysis of wastes varied significantly in the ranges of 2-96 wt%, 2.4-86.8 wt%, and 0.3-83.2 wt%, respectively. Although the present research focused mainly on the premixed method, non-premixed/continuous fast microwave-assisted pyrolysis is still promising and challenging.

An Overview of Temperature Issues in Microwave-Assisted Pyrolysis

Microwave-assisted pyrolysis is a promising thermochemical technique to convert waste polymers and biomass into raw chemicals and fuels. However, this process involves several issues related to the interactions between materials and microwaves. Consequently, the control of temperature during microwave-assisted pyrolysis is a hard task both for measurement and uniformity during the overall pyrolytic run. In this review, we introduce some of the main theoretical aspects of the microwaves–materials interactions alongside the issues related to microwave pyrolytic processability of materials.

Catalytic co-pyrolysis of sugarcane bagasse and waste high-density polyethylene over faujasite-type zeolite

This study investigated the catalytic co-pyrolysis of sugarcane bagasse (SCB) and waste high-density polyethylene (HDPE) over faujasite-type zeolite derived from electric arc furnace slag (FAU-EAFS) in a fixed-bed reactor. The effects of reaction temperature, catalyst-to-feedstock ratio, and HDPE-to-SCB ratio on product fractional yields and chemical compositions were discussed. The co-pyrolysis of SCB and HDPE over FAU-EAFS increased the liquid yield and enhanced the quality of bio-oil. The maximum bio-oil (68.56 wt%) and hydrocarbon yield (74.55%) with minimum yield of oxygenated compounds (acid = 0.57% and ester = 0.67%) were achieved under the optimum experimental conditions of catalyst-to-feedstock ratio of 1:6, HDPE-to-SCB ratio of 40:60, and temperature of 500 °C. The oil produced by catalytic co-pyrolysis had higher calorific value than the oil produced by the pyrolysis of SCB alone.

Co-pyrolysis of biomass and soapstock in a downdraft reactor using a novel ZSM-5/SiC composite catalyst

A ZSM-5/SiC composite catalyst was synthesized and characterized by Brunauer-Emmett-Teller analysis, X-ray diffraction, and scanning electron microscopy in this study. The composite catalyst had the characteristics of ZSM-5 and SiC, and the surface of SiC grew evenly with a layer of ZSM-5. The effect of the composite catalyst on the product distribution and chemical composition in a co-pyrolysis downdraft system was investigated. In a down system with a catalytic temperature of 450 °C, a feed-to-catalyst ratio of 2:1, and a soybean-soapstock-to-straw ratio of 1:1, the proportions of alkanes, olefins, aromatics, and phenoxy compounds were 6.82%, 4.5%, 73.56% and 11.11%, respectively. The composite catalyst combined the catalytic performance of ZSM-5 and SiC, increasing the proportion of aromatics and decreasing the proportion of oxygen-containing compound in the bio-oil. Moreover, the composite catalyst maintained its activity after reusing several times.

Renewable jet-fuel range hydrocarbons production from co-pyrolysis of lignin and soapstock with the activated carbon catalyst

The current study aims to investigate the effects of agricultural waste-derived activated carbon catalyst on the jet-fuel range hydrocarbons distribution from raw biomass pyrolysis under the hydrogen donor condition provided by a solid waste. Ex-situ catalytic fast co-pyrolysis of lignin with and without soapstock was carried out using the corn stover-derived activated carbon catalyst in a facile fixed bed reactor. Results showed that the soapstock, as the hydrogen donor, exhibited a positive synergistic effect with lignin on enhancing the production of valuable aromatics in the obtained bio-oil. Additionally, biomass-derived activated carbon catalyst has the robust catalytic ability to convert pyrolysis vapors into high-density jet fuel-ranged aromatic hydrocarbons rather than phenols with the assistance of soapstock solid waste. Results indicated that the proportions of jet-fuel range aromatics increased monotonically with elevating pyrolytic temperatures from 400 to 550 °C, and the optimal lignin/soapstock ratio was 1:2 with regarding the yield of attained bio-oils. The maximum proportion of jet-fuel ranged aromatics (87.8%) and H₂ concentration (76.4 vol%) could be achieved with the pyrolytic temperature, lignin/soapstock ratio, and catalyst/feedstock ratio of 550 °C, 2:1, and 1:1, respectively. The current study may provide a novel route of converting solid wastes into value-added jet fuels and hydrogen-enriched fuel gases, which will advance the utilization of renewable biomass.

Catalytic co-pyrolysis of Alternanthera philoxeroides and peanut soapstock via a new continuous fast microwave pyrolysis system

Continuous fast microwave catalytic co-pyrolysis of Alternanthera philoxeroides and peanut soapstock was studied using HZSM-5 as catalyst. The effects of catalyst temperature, feedstock-to-catalyst ratio, and A. philoxeroides-to-peanut soapstock ratio on the yield and composition of bio-oil were studied. Experimental results showed that the optimum catalyst temperature was 400 °C. The catalyst increased the proportion of aromatics but reduced the bio-oil yield. The optimum feedstock-to-catalyst ratio was 2:1. A. philoxeroides presented a significant synergistic effect with peanut soapstock, which facilitated the production of aromatics in the bio-oil. The optimum A. philoxeroides-to-peanut soapstock ratio was 1:2.

Numerical simulation and experiment on catalytic upgrading of biomass pyrolysis vapors in V-shaped downer reactors

Catalytic upgrading of biomass pyrolysis vapors is an effective utilization technology of biomass energy. Based on the disadvantages of commonly used reactors, the V-shaped downer reactors were designed to increase gas-solid two-phase turbulent intensity, contact frequency and then increase the catalytic efficiency in short residence time. The catalytic upgrading of pyrolysis vapors in V-shaped downer reactors in terms of hydrodynamics, chemical reaction and residence time distribution were analyzed by CFD simulation and experiment. The results indicate that the solid concentration gradient decreases while flowing down. The overall mass fraction of the bio-oil vapors is around 50%. The mean residence time of catalysts in the V-shaped reactor is 2.0 s-3.0 s. The effects on product yield and residence time distribution were investigated for optimizing product selectivity and the performance of catalysts. In this paper the optimal flow rates of gas and catalysts are v_g = 1.2 m s^-1, v_s = 0.4 m s^-1.

Conversion of woody oil into bio-oil in a downdraft reactor using a novel silicon carbide foam supported MCM41 composite catalyst

This study reports the synthesis of a SiC-MCM41 composite catalyst by a microwave-assisted hydrothermal process and the composite catalyst had the characteristics of MCM41 and SiC, and the surface of SiC grew evenly with a layer of MCM41 after characterization of the catalysts by various means (X-ray diffraction, Brunauer–Emmett–Teller, scanning electron microscopy). The catalyst was applied in the pyrolysis of waste oil to investigate how it influences the bio-oil component proportion compared with no catalyst, only SiC, only MCM41 catalysis and the catalytic effect was also investigated at different temperatures and different catalyst to feed ratios. In a downdraft system with a pyrolysis temperature of 550 °C, a catalyst to feed ratio of 1 : 2, and a catalytic temperature of 400 °C, 32.43% C₅–C₁₂ hydrocarbons and 41.10% mono-aromatics were obtained. The composite catalyst combined the catalytic effect of SiC and MCM41 because it increased the amount of C₅–C₁₂ hydrocarbons and decreased the amount of oxygen-containing compounds in bio-oil. After repeated uses, the composite catalyst still retained the catalytic properties.

Main flow chart of the pyrolysis process using SiC-MCM41 catalyst.

Production of bio-oil from agricultural waste by using a continuous fast microwave pyrolysis system

In this study, a continuous fast microwave-assisted pyrolysis system was developed to produce bio-oil, gas, and biochar from rice straw and Camellia oleifera shell. The effects of different pyrolysis temperatures (400 °C, 500 °C, and 600 °C) and feed rates (rice straw: 25, 45, and 66 g/min; C. oleifera shell: 100, 200, and 400 g/min) on bio-oil production were investigated. Experimental results showed that the yields of bio-oil (31.86 wt%) and gas (54.49 wt%) produced by the microwave-assisted pyrolysis of rice straw increased with increasing temperature. By contrast, the yields of bio-oil (27.45 wt%) and biochar (35.47 wt%) produced by the pyrolysis of C. oleifera shell decreased with increasing temperature. The contents of phenols, aldehydes, and alcohols in bio-oil produced from the shell were higher than those in bio-oil derived from rice straw.