A series of lanthanum/beta-zeolite catalysts was prepared via hydrothermal ion exchange, and characterized by inductively coupled plasma-atomic emission spectroscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, and ammonia temperature-programmed desorption. The lanthanum-doping effect on beta-zeolite catalysts was investigated through catalytic cracking of supercritical methylcyclohexane under the system pressure of 4.0 MPa and the mass flow rate of 1.0 g=s. For lanthanum/beta catalyst of the Cat-2 type, the gas yield of 28.3% and heat sink of 3.35 MJ · kg −1 could be achieved at the temperature of 700°C, much higher than those for the pure beta zeolite without lanthanum modification and for the thermal pyrolysis. Correspondingly, Cat-2 has a better performance on coking inhibition with the reduction of 56.2 and 29.5% at 700°C compared to beta zeolite and thermal cracking. Therefore, it was indicated that beta zeolite with the suitable lanthanum content, still maintaining its high activity and stability of the zeolite framework at high temperature due to lanthanum doping, had a great contribution to high heat sink and coking inhibition at high temperature. Nomenclature c = mass fraction of methylcyclohexane in the residues G = mass flow rate, g∕s I = current, A I 550 = intensity of the peak at 2θ 22.6 deg after calcination at 550°C for 3 h I 850 = intensity of the peak at 2θ 22.6 deg after calcination at 850°C for 30 min m 0 = initial feeding mass of methylcyclohexane, kg m 1 = mass of residues collected after a cracking reaction, kg P C = critical pressure, MPa Q m = heat sink, MJ∕kg R crystal = relative crystallinity T C = critical temperature,°C U = voltage, V W = heating power, W α MCH = conversion of methylcyclohexane, wt. % γ gas = gas yield of methylcyclohexane, % η = thermal efficiency
Chemical looping gasification (CLG) is a promising method to realize the resource utilization of solid waste. Chemical looping co‐gasification (CLCG) attracts much attention as it can fully utilize the synergistic effects between different types of fuels to improve the quality of gasification products. The CLCG characteristics of water hyacinth and different solid wastes, including straw, polypropylene, and sludge, are studied using lean iron ore as oxygen carriers (OCs). It is shown in the results that these solid wastes have synergistic effects on the CLG of water hyacinth to some extent. The addition of straw has a positive impact on gas production and H2/CO ratio, while the introduction of polypropylene and sludge focuses on improving gas production and H2/CO ratio, respectively. In addition, the optimal mixing ratios between water hyacinth and different solid waste are water hyacinth: straw = 50:50; water hyacinth: polypropylene 25:75; and water hyacinth: sludge = 75:25, respectively. The mixing of water hyacinth with polypropylene exhibits better gasification performance, in terms of the total gas yield of 1.27 Nm3 kg−1 and the H2/CO ratio of 1.76 at the mixing ratio of 25:75. This implies that the CLCG of biomass and polypropylene has better application prospect.
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