吸附强化的甲烷水蒸汽重整制氢反应特性

在实验室固定床反应器上研究了采用复合催化剂的吸附强化甲烷水蒸汽重整制氢反应,对吸附强化制氢反应条件进行了考查,得到了实验室条件下的最佳反应条件为温度600～640 ℃,压力0.2 MPa,水碳比4～5.在600 ℃,0.2 MPa,水碳比5的条件下,吸附强化段H2含量高达95.39%,吸附强化段CH4转化率达到81.37%,相对于理论平衡值的吸附强化因子达到26.76%.     

Promotional role of MgO on sorption-enhanced steam reforming of ethanol over Ni/CaO catalysts

This article describes the design and synthesis of MgO-modified Ni/CaO catalysts for sorption-enhanced steam reforming of ethanol. The results show that the introduction of MgO effectively increases the dispersion of CaO via forming MgCa(CO₃)₂ precursor. In the prepared MgO-modified Ni/CaO catalysts, metallic Ni exists around MgO supported on CaO. Both 100% ethanol conversion and >96% hydrogen purity can be stabilized in 10 cycles over the catalyst containing 20 wt% MgO. The interaction between metallic Ni and MgO enhances the sintering resistance of the catalyst. More importantly, reaction pathway studies have confirmed that the formation of CaCO₃ hinders the activation of H₂O on the Ni/CaO catalyst surface, and thus inhibits the conversion of the reaction intermediates including HCO* and CH _x*. MgO can dissociate H₂O to form hydroxyl groups which participate in the conversion of the reaction intermediates, thereby the MgO-modified Ni/CaO catalysts have better catalytic performance and carbon deposition resistance.     

锂基CO2吸附剂在吸附强化甲烷水蒸汽重整制氢中的应用研究进展

简介了吸附强化甲烷水蒸汽重整制氢的研究背景,重点介绍了新型锂基CO2吸附剂(包括Li2ZrO3、Li4SiO4、Na2ZrO3)在吸附强化甲烷水蒸汽重整制氢中的应用研究进展,对新型吸附剂在吸附强化制氢中的应用研究进行了展望。     

The coupling performance during reactive sorption enhanced reforming (ReSER) process: Simulation and experimental studies

The coupling performance of nano-CaO carbonation with the steam methane reforming (SMR) during reactive sorption enhanced reforming process (ReSER) for hydrogen production was studied by simulation and experimental evaluation. A two-dimensional axial symmetric pseudo-homogeneous mathematic model was established based on nano-CaO carbonation kinetics with the Boltzmann equation style and SMR reaction kinetics. The coupling performance was studied by varying carbonation rate constant (k_carb) and the maximum carbonation conversion (X_max) in the model. The mathematic model was numerically solved by the COMSOL Multiphysics software and experimentally evaluated using commercial nano-CaO as the CO₂ adsorbent. An average relative deviation of 3.86% of CH₄ conversion was obtained between the simulated and experimental results. The simulation results indicated the conversion of the CH₄ was improved from 88% to 95.3% by increasing k_carb from 1.6 s⁻¹ to 5.74 s⁻¹ and the period of pre-breakthrough time could be extended from 2 min to 20 min by increasing X_max from 0.3 to 0.9. CH₄ conversion of maximum 94.1% when reaction was under 650 °C and 1 bar, the highest molar fraction of H₂ of 99.7% when reaction at 600 °C and 1 bar, and the maximum enhancement factor of 45.4% was obtained at 576.3 °C, 2.8 bar.     

Pt–calcium cobaltate enables sorption-enhanced steam reforming of glycerol coupled with chemical-looping CH4 combustion

Sorption-enhanced steam reforming (SESR) process is usually highly energy intensive in producing high-purity hydrogen. Herein, the sorbent decarbonation was conducted in the presence of O₂ to enable the exothermic reaction between CaO and CoO_x to form calcium cobaltate (CCO). By utilizing CCO as oxygen carrier (OC), the chemical-looping methane combustion was employed prior to the SESR of glycerol (SESRG), by which CCO was prereduced to Co catalysts and CaO sorbent, thereby significantly improving the H₂ yield from SESRG. With a Pt-doped CCO acting as precatalyst, CO₂ sorbent, and OC, we realized 70% CH₄ conversion and 96 vol% H₂ with 120% yield (based on glycerol) for 20 cycles, and the excess H₂ was due to steam gasification of coke. The promoting effects of Pt toward CH₄ conversion and H₂ production were rationalized by CH₄ temperature-programmed reduction, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. Our results demonstrate the feasibility of process integration enabled by multifunctional materials.