Adolfo Iulianelli

Advances on methane steam reforming to produce hydrogen through membrane reactors technology: A review

ABSTRACT Methane steam reforming is the most common industrial process used for almost the 50% of the world’s hydrogen production. Commonly, this reaction is performed in fixed bed reactors and several stages are needed for separating hydrogen with the desired purity. The membrane reactors represent a valid alternative to the fixed bed reactors, by combining the reforming reaction for producing hydrogen and its separation in only one stage. This article deals with the recent progress on methane steam reforming reaction, giving a short overview on catalysts utilization as well as on the fundamentals of membrane reactors, also summarizing the relevant advancements in this field.

Hydrogen Production by Ethanol Steam Reforming: Experimental Study of a Pd-Ag Membrane Reactor and Traditional Reactor Behaviour

In this experimental work, the ethanol steam reforming reaction for producing hydrogen was studied in both a traditional reactor (TR) and a Pd-Ag dense membrane reactor (MR). Both reactors have been packed with a commercial Ru-based catalyst. The experimental tests have been performed in the temperature range 400-500 °C and in the pressure range 2.0-3.6 bar.The results are reported in terms of ethanol conversion, hydrogen production, product selectivities and hydrogen recovery (for the MR only). It has been found that the MR is able to increase the ethanol conversion as well as increase the hydrogen production with respect to a traditional reactor. Moreover, part of the hydrogen produced in the MR is recovered as a CO-free hydrogen stream and is suitable for feeding a PEM fuel cell system.

Supported Pd-Au Membrane Reactor for Hydrogen Production: Membrane Preparation, Characterization and Testing

A supported Pd-Au (Au 7wt%) membrane was produced by electroless plating deposition. Permeation tests were performed with pure gas (H2, H2, N2, CO2, CH4) for long time operation. After around 400 h under testing, the composite Pd-Au membrane achieved steady state condition, with an H2/N2 ideal selectivity of around 500 at 420 °C and 50 kPa as transmembrane pressure, remaining stable up to 1100 h under operation. Afterwards, the membrane was allocated in a membrane reactor module for methane steam reforming reaction tests. As a preliminary application, at 420 °C, 300 kPa of reaction pressure, space velocity of 4100 h−1, 40% methane conversion and 35% hydrogen recovery were reached using a commercial Ni/Al2O3 catalyst. Unfortunately, a severe coke deposition affected irreversibly the composite membrane, determining the loss of the hydrogen permeation characteristics of the supported Pd-Au membrane.

Glycerol Production and Transformation: A Critical Review with Particular Emphasis on Glycerol Reforming Reaction for Producing Hydrogen in Conventional and Membrane Reactors

Glycerol represents an emerging renewable bio-derived feedstock, which could be used as a source for producing hydrogen through steam reforming reaction. In this review, the state-of-the-art about glycerol production processes is reviewed, with particular focus on glycerol reforming reactions and on the main catalysts under development. Furthermore, the use of membrane catalytic reactors instead of conventional reactors for steam reforming is discussed. Finally, the review describes the utilization of the Pd-based membrane reactor technology, pointing out the ability of these alternative fuel processors to simultaneously extract high purity hydrogen and enhance the whole performances of the reaction system in terms of glycerol conversion and hydrogen yield.

Water Gas Shift Reaction in Pd-Based Membrane Reactors

Water-gas shift reaction is an important industrial reaction, used for producing synthesis gas and ammonia as well as pure hydrogen for supplying at PEM fuel cells. In this work, an overview on water gas shift reaction performed in Pd-based membrane reactors is shown, paying particular attention to the influence on the performances of some operating variables such as reaction temperature, reaction pressure, H2O/CO molar ratio and sweep gas.

Membrane reactors for methane steam reforming (MSR)

Abstract Methane steam reforming (MSR) is the most common and cost-effective method for hydrogen production, and it contributes about 50% of the worlds hydrogen production. Although MSR is a mature technology, it suffers from significant disadvantages such as mass and heat transfer issues and coke deposition during the reaction. Industrially, the MSR reaction is carried out in conventional reactors (CRs) and, in order to obtain a highly pure hydrogen stream, several steps are necessary, such as the reduction of carbon monoxide content in the reformate stream by water gas shift reactors, pressure swing adsorption, and further hydrogen separation/purification devices. Therefore, in order to intensify the whole process, a membrane reactor can be used as alternative solution to conventional systems. In particular, the use of a hydrogen perm-selective membrane inside of a reactor allows the combination of the chemical reaction and hydrogen separation in only one tool. As a result, high-purity hydrogen, methane conversion, and hydrogen production enhancement are obtained as well as the possibility to perform the MSR reaction at milder operating conditions than CRs. Therefore, in this chapter, the relevant progress achieved so far, the most relevant topics of MSR via membrane reactor technology, and the effects of the most important parameters affecting MSR in membrane reactors are described and critically reviewed. In addition, an overview on the mathematical models used for simulating the MSR reaction in a membrane reactor is also presented and discussed.

Hydrogen Production for PEM Fuel Cells

Today, hydrogen is seen as the most convenient energy carrier for a number of applications and, particularly, for proton exchange membrane fuel cells (PEMFCs). In the specialized literature, many studies address the production of hydrogen derived from renewables. Therefore, the scope of this chapter is to review the recent findings about hydrogen generation from reforming processes of bio-sources combined with membrane reactor technology. A deep discussion is presented about the general classification of the membranes, with special attention being paid toward palladium-based membranes. Furthermore, an overview on the representative results on the reforming of ethanol and methanol as renewable sources performed in membrane reactors is given.

Ethanol From Biomass

Abstract Nowadays, the world’s energy requirements are based on the use of fossil fuels. Rapid growth in both global energy demand and carbon dioxide emissions associated with the use of these fuels have driven the research for alternative sources, which are renewable and have a lower environmental impact. Ethanol is considered one of them. In fact, it is considered one of the better biofuels for transport: it can be burned directly or blended with petrol to improve fuel combustion in vehicles, resulting in lower CO 2 emission to reduce greenhouse gases in the atmosphere. The optimization of the ethanol production processes from lignocellulosic biomass is considered an important research from both industrial and research point of view. In function of the nature of the raw material, it is possible to distinguish these three different feedstock generations. In the first generation, the substrate consists mainly of seeds, potato, and grains and the production process consists of the purification of simple sugars to obtain ethanol. Nevertheless, the first generation of biofuels has been perceived as sustainable mainly from both an environmental and limitation in food supply point of view. This has meant that research has switched to the development of more advanced technology to obtain an energy sustainability to minimize greenhouse gases emission. For these reasons, other two different production processes have been developed, focusing on the fermentation of cellulose and hemicellulose from mainly agricultural wastes (second generation) and algae (third generation). This chapter represents a critical analysis of published data on application and potentiality of the bioethanol production from first, second and third generation of feedstock.

Advances in Methanol Production and Utilization, with Particular Emphasis toward Hydrogen Generation via Membrane Reactor Technology

Methanol is currently considered one of the most useful chemical products and is a promising building block for obtaining more complex chemical compounds, such as acetic acid, methyl tertiary butyl ether, dimethyl ether, methylamine, etc. Methanol is the simplest alcohol, appearing as a colorless liquid and with a distinctive smell, and can be produced by converting CO2 and H2, with the further benefit of significantly reducing CO2 emissions in the atmosphere. Indeed, methanol synthesis currently represents the second largest source of hydrogen consumption after ammonia production. Furthermore, a wide range of literature is focused on methanol utilization as a convenient energy carrier for hydrogen production via steam and autothermal reforming, partial oxidation, methanol decomposition, or methanol–water electrolysis reactions. Last but not least, methanol supply for direct methanol fuel cells is a well-established technology for power production. The aim of this work is to propose an overview on the commonly used feedstocks (natural gas, CO2, or char/biomass) and methanol production processes (from BASF—Badische Anilin und Soda Fabrik, to ICI—Imperial Chemical Industries process), as well as on membrane reactor technology utilization for generating high grade hydrogen from the catalytic conversion of methanol, reviewing the most updated state of the art in this field.

Progress in Methanol Steam Reforming Modelling via Membrane Reactors Technology

Hydrogen has attracted growing attention for various uses, and, particularly, for polymer electrolyte membrane fuel cells (PEMFCs) supply. However, PEMFCs need high grade hydrogen, which is difficult in storing and transportation. To solve these issues, hydrogen generation from alcohols and hydrocarbons steam reforming reaction has gained great consideration. Among the various renewable fuels, methanol is an interesting hydrogen source because at room temperature it is liquid, and then, easy to handle and to store. Furthermore, it shows a relatively high H/C ratio and low reforming temperature, ranging from 200 to 300 °C. In the field of hydrogen generation from methanol steam reforming reaction, a consistent literature is noticeable. Despite various reviews that are more devoted to describe from an experimental point of view the state of the art about methanol steam reforming reaction carried in conventional and membrane reactors, this work describes the progress in the last two decades about the modelling studies on the same reaction in membrane reactors.