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This study systematically investigated the co-slagging characteristics of high-rank coal and biomass ashes considering entrained flow slagging gasifier. Despite favourable performance parameters, coal might not be feasible for entrained flow gasification because of not forming slag within the gasifier operating temperature (1200–1500 °C). To overcome this issue, co-gasification can be a potential solution, which simultaneously helps to reduce the carbon footprint and environmental impact. Hence, this study studied the feasibility of co-gasification of coal and biomass by testing co-slagging behaviour of bituminous coal and pine park biomass ashes. The slag viscosity is measured using a Brookfield DV-III Ultra rheometer coupled with a high-temperature furnace. Results show that pure coal ash does not form slag using the maximum furnace temperature of 1670 °C. However, co-slagging by 50/50 (wt./wt.) ratio of coal and biomass ash (PB50) significantly drops the slagging temperature due to the higher fluxing agents (i.e. CaO) in biomass ash. The temperature of critical viscosity was determined to be 1390 °C using PB50 ash, which maintained the maximum industrial viscosity limit of 25 Pa s up to the temperature of 1360 °C.

This study investigates the yield and quality of bio-oil produced from catalytic and non-catalytic pyrolysis of microalgae Chlorella vulgaris using Ni supported zeolite (Si/Al = 30) prepared by two different methods, ion exchange (IE) and wet impregnation (WI) to examine the effect of catalyst preparation methods on the bio-oil quality. The experiments were also conducted to investigate the effect of different temperatures (300–600 °C) and catalyst to algae ratio (1:5, 1:2, 1:1 and 2:1) on the yield and quality of bio-oil. The results showed that catalytic pyrolysis using Ni supported zeolites produced high hydrocarbon, less oxygenated and acid compounds compared to non-catalytic pyrolysis. The catalyst preparation method did not affect the yield but had an effect on the bio-oil composition. The results obtained from this study are useful in developing the catalytic pyrolysis process to refine bio-oils for commercial use.

Mechanism of CO2 adsorption on amine loaded SBA-15 sorbents with varying amine coverage has been assessed using thermogravimetric analysis (TGA) and in-situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). TGA study showed that sorbent adsorption capacities increased by 122–153% with CO2 concentrations (5–80%) in the gas at 50/75 °C. The DRIFTS studies indicate that low amine loaded sorbents exhibit higher uptakes with an increase in CO2 concentrations which is attributed to the mode of CO2 adsorption i.e. 1:1 CO2 to amine forming carbamic acid. At higher amine loadings CO2 is adsorbed following the 1:2 CO2 to amine forming carbamate-ammonium ions pair resulting in lower adsorption capacities per amine site. The studies also showed an increase in carbamic acid formation with pressure from 100 to 500 kPa at low amine loadings and both carbamic acid and carbamates at higher amine loadings. The paper provides insights into the mechanistic understanding of CO2 adsorption behaviour of the varyingly covered amines on the SBA-15 support with a change in concentration and pressure of CO2. The current work presents the conditions to alter the CO2 adsorption mechanism on amine sites with potential application in CO2 conversion to chemicals.

This two-part study firstly investigated Tetraselmis suecica grown in different CO2 (0.04–15% v/v) concentration through indoor and outdoor cultivation systems. A high CO2 concentration led to a high lipid content, and low nitrogen and oxygen content, which are desirable for transport fuel production. Pyrolysis characteristics were investigated by TG-IR and synchrotron IR microscopy. The results show Tetraselmis suecica grown in 10% CO2 had the highest decomposition rate corresponding to more volatile products produced during the main thermal cracking stage and derived from protein-and lipid-corresponding functional groups. Moreover, a high reaction temperature and CO2 concentration resulted in a low retention of surface functional groups. The nitrogen functional groups initially decomposed at a temperature range of 250–300 °C and still remained at 550 °C, while the lipid-corresponding functional groups completely disappeared at a temperature range of 400–500 °C. Besides, the decomposition of chemical components followed the order of carbohydrate, protein and lipid.

Catalytic pyrolysis is a useful technique for the conversion of scrap tyres into liquid fuels. Zeolite catalysts were employed in the pyrolysis of scrap tyres for the production of aromatic rich fuel. Deactivation of zeolite catalysts during pyrolysis reaction was investigated which played an important role in the product quality and composition. Herein, the performance of microporous zeolite catalysts and mesoporous MCM-41 catalyst was evaluated in a two-stage fixed bed reactor for the pyrolysis of scrap tyres. Comparative studies showed the increase in the production of aromatic compounds up to 23.7% over zeolite catalyst as compared to 18.7% over MCM-41 catalyst. However, Zeolite Y catalyst exhibited higher coke formation led to the rapid deactivation. The stability of zeolite catalysts is addressed by the incorporation of Cerium metal within the framework of two zeolite catalysts namely Zeolite Y and ZSM-5 through the ion-exchange technique. Parent and spent catalysts were characterised using synchrotron FT-IR spectroscopy, temperature-programmed desorption of ammonia (NH3-TPD), N2 Physisorption, scanning electron microscopy (SEM), inductively coupled plasma-optical emission spectrometry (ICP-OES), energy-dispersive X-ray spectroscopy (EDX), and hydrogen temperature-programmed reduction (H2-TPD). A higher percentage of aromatics were produced over the large pore Zeolite Y. Cerium ion-exchange decreased the formation of coke from 8.1% to 5.7% over submicron and large pore Zeolite Y catalyst. Moreover, naphthalene production decreased over both Ce-Zeolite Y and Ce-ZSM-5.