Zhenting Yu

Production of bio-oil and biochar from soapstock via microwave-assisted co-catalytic fast pyrolysis.

In this study, production of bio-oil and biochar from soapstock via microwave-assisted co-catalytic fast pyrolysis combining the advantages of in-situ and ex-situ catalysis was performed. The effects of catalyst and pyrolysis temperature on product fractional yields and bio-oil chemical compositions were investigated. From the perspective of bio-oil yield, the optimal pyrolysis temperature was 550°C. The use of catalysts reduced the water content, and the addition of bentonite increased the bio-oil yield. Up to 84.16wt.% selectivity of hydrocarbons in the bio-oil was obtained in the co-catalytic process. In addition, the co-catalytic process can reduce the proportion of oxygenates in the bio-oil to 15.84wt.% and eliminate the N-containing compounds completely. The addition of bentonite enhanced the BET surface area of bio-char. In addition, the bio-char removal efficiency of Cd2+ from soapstock pyrolysis in presence of bentonite was 27.4wt.% higher than without bentonite.

Hydrothermal pretreatment of bamboo sawdust using microwave irradiation

In the present study, the effect of temperature and residence time during microwave hydrothermal pretreatment (MHT) on hydrochar properties and pyrolysis behaviors was investigated. Experimental results indicated that higher heating value (HHV) and fixed carbon content gradually increased with increased pretreatment severity. Obvious reduction of oxygen content was found under MHT at 230°C-15min and 210°C-35min. Although lower mass yield was observed under severe conditions, corresponding energy yield was relatively higher. Crystallinity indexes of hydrochar demonstrated an upward trend with increased residence time. Unlike hydroxyl group, dissociation of acetyls was more favorable under prolonged residence time rather than increased temperature. Peaks in thermogravimetric and derivative thermogravimetric curves shifted to higher temperature region under severe conditions, indicating better thermal stability. Py-GC/MS analysis suggested that acids content was decreased but sugars increased with increased MHT severity. Moreover, compared to temperature, residence time was mainly responsible for acetic acid formation.

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

Fast microwave-assisted catalytic co-pyrolysis of Chromolaena odorata (C. odorata) and soybean soapstock with HZSM-5 as an ex-situ catalyst was investigated. Effects of catalytic temperature, feedstock: catalyst ratio and C. odorata: soybean soapstock ratio on the yield and composition of the bio-oil were discussed. Results showed that catalytic temperature greatly influenced the bio-oil yield. Co-pyrolysis of C. odorata and soybean soapstock improved the bio-oil yield, and the maximum bio-oil yield of 55.14% was obtained at 250 °C. However, the addition of HZSM-5 decreased bio-oil yield but improved the quality of bio-oil. Moreover, the proportion of oxygen-containing compounds decreased dramatically with the addition of soybean soapstock. The C. odorata: soybean soapstock ratio of 1:2 and feedstock: catalyst ratio of 2:1 were the optimal condition to upgrade the bio-oil. In addition, the resulted biochar contained various essential elements and could be used as soil repair agent.

Catalytic fast pyrolysis of torrefied corn cob to aromatic hydrocarbons over Ni-modified hierarchical ZSM-5 catalyst

Catalytic fast pyrolysis (CFP) of torrefied corn cob using Ni-modified hierarchical ZSM-5 catalyst was conducted in this study. The prepared catalysts were characterized by N2 adsorption and desorption (N2-BET), X-ray diffraction (XRD), and temperature-programmed desorption of NH3 (NH3-TPD). NaOH solution treatment resulted in the lower peak intensities of hierarchical ZSM-5 catalyst in the XRD patterns while Ni modification improved the catalyst framework. In addition, NaOH solution treatment created some mesopores or macropores, but the incorporation of Ni reduced BET surface area and volume of micropores. Though the addition of Ni lowered the acidity of catalyst, Ni-modified hierarchical ZSM-5 catalyst led to higher yields and of aromatic hydrocarbons. What is more, hierarchical ZSM-5 catalysts significantly improved the selectivities of mono-aromatics. Kinetic analysis shows that CFP of torrefied corn cob was second-order reaction and the addition of Ni can obtain a lower activation energy compared with hierarchical ZSM-5 catalyst.