With increased availability and decreased cost, ethanol is potentially a promising platform molecule for the production of a variety of value-added chemicals. In this review, we provide a detailed summary of recent advances in catalytic conversion of ethanol to a wide range of chemicals and fuels. We particularly focus on catalyst advances and fundamental understanding of reaction mechanisms involved in ethanol steam reforming (ESR) to produce hydrogen, ethanol conversion to hydrocarbons ranging from light olefins to longer chain alkenes/alkanes and aromatics, and ethanol conversion to other oxygenates including 1-butanol, acetaldehyde, acetone, diethyl ether, and ethyl acetate.

Recent Advances in Catalytic Conversion of Ethanol to Chemicals

High temperature CO2 sorbents and their application for hydrogen production by sorption enhanced steam reforming process

This Review describes recent advances in the design, synthesis, reactivity, selectivity, structural, and electronic properties of the catalysts for reforming of a variety of oxygenates (e.g., from simple monoalcohols to higher polyols, then to sugars, phenols, and finally complicated mixtures like bio-oil). A comprehensive exploration of the structure–activity relationship in catalytic reforming of oxygenates is carried out, assisted by state-of-the-art characterization techniques and computational tools. Critical emphasis has been given on the mechanisms of these heterogeneous-catalyzed reactions and especially on the nature of the active catalytic sites and reaction pathways. Similarities and differences (reaction mechanisms, design and synthesis of catalysts, as well as catalytic systems) in the reforming process of these oxygenates will also be discussed. A critical overview is then provided regarding the challenges and opportunities for research in this area with a focus on the roles that systems of ...

Catalytic Reforming of Oxygenates: State of the Art and Future Prospects.

Hydrogen production from ethanol is regarded as a promising way for energy sustainable development, which is undergoing an explosive growth over the last decade. Besides operating conditions, hydrogen yield greatly dependent on the nature of metal and the support selected. To date, Rh based catalysts proved to be the most active systems due to the fact that Rh possessed the greatest capacity toward C–C bond cleavage. Support also played a critical role in terms of hydrogen selectivity and stability. MgO, CeO2 and La2O3 etc were evidenced as suitable supports because of their basic characteristic and/or redox capacity. A detailed analysis based on the spectroscopic technique revealed that reaction pathways proceeded along a mono-functional or bi-functional mechanism according to the types of active metal and support. Ethanol dehydrogenation and/or dehydration reaction mainly occurred on the support, and the diffusion/transformation of the intermediates took place at the metal–support interface. Meanwhile, active metal accelerated the decomposition reaction. The observed catalyst deactivation was normally assigned to the coke formation, active metal sintering and/or oxidation as well as the impurity in crude bio-ethanol. Hence, the scope of this review is to address the present progress in ethanol reforming for hydrogen production including catalyst development and the analysis of the reaction mechanism and kinetics in order to shed light on the design of high efficient catalyst systems and the fundamental understanding of ethanol conversion at the molecular level.

Hydrogen production from ethanol reforming: Catalysts and reaction mechanism

The objective of this review is to analyze potential technologies and their baseline performance of producing hydrogen from catalytic steam reforming of biodiesel byproduct glycerol. High oxygen content and high impurity level of biodiesel byproduct glycerol, as well as the complex intermediates and high coking potential in its thermal degradation, make the modeling, design, and operation of glycerol steam reforming a challenge. Thermal decomposition characterization of biodiesel byproduct glycerol was covered, and the recent developments and methods for high-purity hydrogen production from glycerol steam reforming were illustrated. The thermodynamics constraint of water gas shift reaction can be overcome by the sorption-enhanced steam reforming process, which integrated catalytic steam reforming, water gas shift reaction and in-situ CO2 removal at high temperatures in a single stage reactor. The effectiveness of both the enhanced H2 production and the use of CO2 sorbents have been demonstrated and discussed. The technical challenges to achieve a stable high-purity hydrogen production by the sorption-enhanced steam reforming process included extending operation time, selecting suitable sorbents, finding a way for continuous reaction-regeneration of catalyst and sorbent mixture and improving process efficiencies. The continuous sorption-enhanced steam reforming of glycerol was designed by a simultaneous flow concept of catalyst and sorbent for continuous reaction-regeneration using two slow moving-bed reactors for high-purity hydrogen production and CO2 capture, and in this process, catalyst and sorbent were run in nearly fresh state for H2 production. The sorption-enhanced chemical-looping reforming was also demonstrated. The paper discusses some issues and challenges, along with the possible solutions in order to help in efficient production of hydrogen from catalytic steam reforming of biodiesel byproduct glycerol.

Hydrogen production from catalytic steam reforming of biodiesel byproduct glycerol: Issues and challenges

Steam reforming of ethanol for hydrogen production: Thermodynamic analysis including different carbon deposits representation

Steam reforming of ethanol (SRE) on a Ni/Al2O3 catalyst was studied. The effects of the operating conditions and catalyst nature on the course of reaction were evaluated. Hydrogen was generated in the temperature range between 100 and 600°C. A mechanism was used to explain the reaction pathways. A commercial hydrotalcite-like sorbent arranged in a multilayer pattern of catalyst and sorbent was used for CO2-uptake to enhance hydrogen production. The concept of sorption enhanced reaction process on SRE is illustrated by the operation of catalyst and CO2-sorbent at 400°C. A lower flow rate regime and multilayer pattern system enhances hydrogen production in the initial breakthrough periods. CO appears in traces in the product gas stream. © 2011 Canadian Society for Chemical Engineering

Steam reforming of ethanol on a Ni/Al2O3 catalyst coupled with a hydrotalcite‐like sorbent in a multilayer pattern for co2 uptake

A thermodynamic analysis is performed with a Gibbs free energy minimization method to compare the conventional steam reforming of ethanol (SRE) process and sorption-enhanced SRE (SE-SRE) with three different sorbents, namely, CaO, Li2ZrO3, and hydrotalcite-like compounds (HTlc). As a result, the use of a CO2 adsorbent can enhance the hydrogen yield and provide a lower CO content in the product gas at the same time. The best performance of SE-SRE is found to be at 500 °C with an HTlc sorbent. Nearly 6 moles hydrogen per mole ethanol can be produced, when the CO content in the vent stream is less than 10 ppm, so that the hydrogen produced via SE-SRE with HTlc sorbents can be directly used for fuel cells. Higher pressures do not favor the overall SE-SRE process due to lower yielding of hydrogen, although CO2 adsorption is enhanced.

Sorption-Enhanced Steam Reforming of Ethanol: Thermodynamic Comparison of CO2 Sorbents

Oxidative steam reforming of glycerol for hydrogen production: Thermodynamic analysis including different carbon deposits representation and CO2 adsorption

F. Díaz Alvarado

Papers

Steam reforming of ethanol for hydrogen production: Thermodynamic analysis including different carbon deposits representation

Steam reforming of ethanol on a Ni/Al2O3 catalyst coupled with a hydrotalcite‐like sorbent in a multilayer pattern for co2 uptake

Sorption-Enhanced Steam Reforming of Ethanol: Thermodynamic Comparison of CO2 Sorbents

Oxidative steam reforming of glycerol for hydrogen production: Thermodynamic analysis including different carbon deposits representation and CO2 adsorption