Chemical engineer Inés Reyero Zaragoza proposed the substitution of methanol by ethanol for the production of biodiesel and the use of a heterogeneous catalyst, which will «result in a reduction of costs and in the environmental impact associated with the production of this biofuel.» One of the novel contributions of her research has been the synthesis and identification of a new compound the characteristics of which make it «a very good candidate for developing heterogeneous catalysts.»

Ms. Reyero’s thesis, «Advances in biodiesel production: ethanolysis and new heterogeneous catalysts,» was directed by Professor Luis Gandía Pascual and Professor María Cruz Arzamendi Manterola, from the Department of Applied Chemistry at the UPNA, and was awarded an Outstanding with Honours PhD.

Dr. Reyero explains that, in chemical terms, biodiesel production is based on a reaction known as transesterification. «Vegetable oils are made to react with an alcohol, usually methanol, producing biodiesel and glycerine, a secondary product that has varied applications once purified.» For the reaction to take place a suitable catalyst is needed. «Conventional industrial processes normally use catalysts that are labelled homogeneous because they are soluble in one of the reagents, specifically in alcohol.»

The use of ethanol

In this research ethanol was used instead of methanol. The latter is made from fossil-origin raw materials, while ethanol can be obtained from renewable resources (and is thus known as bioethanol). «We have shown that biodiesel synthesis reactions have very different behaviour depending on what kind of alcohol is used. For example, while with methanol the system is biphasic, using ethanol involves a homogeneous reaction medium and single liquid phase.»

The practical consequences of these variations are relevant. On the one hand, on using ethanol the speed of reaction is very much greater and, thus, there is a greater capacity of production of the reactors. «Nevertheless, on the other hand, the homogeneous character of the reaction complicates the separation of the products and favours the formation of soaps, which contaminate these products, especially glycerine.»

The author of the PhD explains why heterogeneous catalysts are used instead of homogeneous: «the homogeneous ones currently employed are highly effective, but they cannot be reused and they contaminate the products, and so costly separation and purification stages are needed to obtain biodiesel and glycerine in sufficient quantities to be commercially viable. Moreover, all these processes produce large amounts of waste water that also need to be suitably treated.»

Novel contributions

One novel contribution in the course of this research has been the synthesis and identification of a new compound — calcium glycerolate — «which notably surpasses calcium oxide and glyceroxide in stability and makes it a very good candidate for the development of heterogeneous catalysts for the synthesis of biodiesel.»

Ms. Reyero has also used structured catalysts which, in the active phase, are deposited on ceramic or metallic structures. This enables the passage of the reaction medium and facilitates the transformation of the reagents into products — biodiesel and glycerine in this case. Thus, the separation of the catalyst from the reaction medium is avoided, and its reuse facilitated. «The use of structured catalysts is highly novel in the field of biodiesel production and has meant an important technological advance» pointed out the researcher, «and so, in this sense, this thesis can be considered pioneering.»

During the AVS 61st International Symposium Exhibition, being held November 9-14, 2014, in Baltimore, Md., the team will describe their process for creating lithium-oxygen (Li-O2) battery cells.

Carbon nanotubes are typically grown on two-dimensional or planar substrates, but the structure developed by the team is considered «3-D» because the carbon nanotubes are grown on a porous, «sponge-like» foam structure made of nickel coated with aluminum oxide ceramic.

Batteries usually consist of an anode, cathode and electrolyte; the researchers’ 3-D structure forms the «cathode» part of the battery.

«Our team developed self-standing, catalyst-decorated carbon nanotube cathodes for Li-O2 batteries using atomic layer deposition (ALD) and electrochemical deposition methods,» said Marshall Schroeder, a member of the Rubloff Research Group in Materials Science and Engineering at the University of Maryland. «And we also have unique capabilities for in situ characterization via scanning electron microscopy and X-ray photoelectron spectroscopy for elemental analysis of pristine electrodes and at different points during cycling.»

How does the team build their battery cathode? First, they use a nickel foam current collector to deposit a thin layer (~5nm) of aluminum oxide using ALD. This is chased by a layer of iron, sputtered as a growth catalyst for chemical vapor deposition (CVD) of carbon.

The ALD layer «acts as a diffusion barrier to keep the growth catalyst from diffusing into the nickel foam during the high-temperature carbon growth process,» Schroeder explained. «The type of carbon growth is heavily dependent on the CVD process parameters — catalyst ripening temperature/time, growth time/temperature, precursor type, and flow rate, etc. — so optimization of the growth process was required to achieve a vertically aligned carbon nanotube architecture.»

These structures were put to the test as cathodes in lithium oxygen cells, and the team discovered that the optimized growth process resulted in a hierarchical pore structure featuring dense carpets of vertically aligned carbon nanotubes on a 3-D current collector scaffold.

Preliminary studies of this cathode structure show promising results for oxygen reduction reaction (ORR) performance, according Schroeder. «For the oxygen evolution reaction (OER), continued studies will focus on optimization of the electrode performance via decoration with ALD-deposited catalysts,» he adds. «We’ve also started studying the catalyst performance on other carbon nanotube substrates and now have a preliminary fundamental understanding of the catalyst chemistries developed by our team.»

The team’s work shows that combining their ALD capabilities with the unique structure of the 3-D cathode may «significantly improve the performance of one of the most promising next-generation lithium battery technologies,» Schroeder noted.

Current approaches to generating hydrogen as a power source are anything but environmentally friendly. Obtaining hydrogen through steam reforming and electrolysis of water — the splitting of water into hydrogen and oxygen by applying an electric current — requires high energy input and fossil fuels. In contrast, the process of ethanol steam reforming (ESR) uses ethanol derived from renewable biomass to produce hydrogen and other products.

One drawback of ESR, however, is that it requires high reaction temperatures to proceed and therefore a catalyst is needed to spur on the reaction. Another downside of ESR is that it often produces carbon monoxide as a byproduct, which is toxic and can also lead to poisoning of hydrogen fuel cells.

Luwei Chen, Armando Borgna and colleagues at the A*STAR Institute of Chemical and Engineering Sciences have developed an iron-promoted rhodium-based catalyst on a calcium-modified aluminum oxide support for ESR. This catalyst enables hydrogen to be generated more efficiently with less environmental damage as the reaction can occur at temperatures as low as 350 degrees Celsius and produce almost no carbon monoxide as a byproduct. The presence of iron oxide enables carbon monoxide to be converted into carbon dioxide and hydrogen via a reaction known as the water-gas shift reaction. Thus, the iron promotion effect on the rhodium-based catalyst is the key to removing carbon monoxide — something that is exceedingly difficult to achieve on rhodium alone.

Additional benefits of ESR are the commercial advantages stemming from the catalyst being quite stable and having a long active lifetime. This means that the catalyst will permit long cycle lengths, minimize the regeneration frequency and reduce the operational downtime for on-board steam reformers. Chen explains that these factors are «essential for maintaining profitable operations in reforming units. Similarly, a stable catalyst would reduce the operating cost for an on-board reformer.»

Chen notes that the catalyst will enable «better operational flexibility in terms of economics and on-board reformer size (since carbon monoxide purification units can be removed),» which she says will «make a significant impact in the design of efficient and simple on-board reactors.» Hence, this research is promising for advancing the realization of small-scale on-board reformers for hydrogen-powered cars.

Current approaches to generating hydrogen as a power source are anything but environmentally friendly. Obtaining hydrogen through steam reforming and electrolysis of water — the splitting of water into hydrogen and oxygen by applying an electric current — requires high energy input and fossil fuels. In contrast, the process of ethanol steam reforming (ESR) uses ethanol derived from renewable biomass to produce hydrogen and other products.

One drawback of ESR, however, is that it requires high reaction temperatures to proceed and therefore a catalyst is needed to spur on the reaction. Another downside of ESR is that it often produces carbon monoxide as a byproduct, which is toxic and can also lead to poisoning of hydrogen fuel cells.

Luwei Chen, Armando Borgna and colleagues at the A*STAR Institute of Chemical and Engineering Sciences have developed an iron-promoted rhodium-based catalyst on a calcium-modified aluminum oxide support for ESR. This catalyst enables hydrogen to be generated more efficiently with less environmental damage as the reaction can occur at temperatures as low as 350 degrees Celsius and produce almost no carbon monoxide as a byproduct. The presence of iron oxide enables carbon monoxide to be converted into carbon dioxide and hydrogen via a reaction known as the water-gas shift reaction. Thus, the iron promotion effect on the rhodium-based catalyst is the key to removing carbon monoxide — something that is exceedingly difficult to achieve on rhodium alone.

Additional benefits of ESR are the commercial advantages stemming from the catalyst being quite stable and having a long active lifetime. This means that the catalyst will permit long cycle lengths, minimize the regeneration frequency and reduce the operational downtime for on-board steam reformers. Chen explains that these factors are «essential for maintaining profitable operations in reforming units. Similarly, a stable catalyst would reduce the operating cost for an on-board reformer.»

Chen notes that the catalyst will enable «better operational flexibility in terms of economics and on-board reformer size (since carbon monoxide purification units can be removed),» which she says will «make a significant impact in the design of efficient and simple on-board reactors.» Hence, this research is promising for advancing the realization of small-scale on-board reformers for hydrogen-powered cars.

A study of the new cells appears online today in the American Chemical Society journal ACS Catalysis.

Fuel cells convert energy into electricity through a chemical reaction between a fuel and an oxygen-rich source such as air. If a continuous flow of fuel is provided, a fuel cell can generate electricity cleanly and cheaply. While batteries are used commonly to power electric cars and generators, fuel cells also now serve as power generators in some buildings, or to power fuel-cell vehicles such as prototype hydrogen-powered cars.

«The major advance in this research is the ability to use Jet Propellant-8 directly in a fuel cell without having to remove sulfur impurities or operate at very high temperature,» says the study’s senior author, Shelley Minteer, a University of Utah professor of materials science and engineering, and also chemistry. «This work shows that JP-8 and probably others can be used as fuels for low-temperature fuel cells with the right catalysts.» Catalysts are chemicals that speed reactions between other chemicals.

In the new study, the University of Utah team investigated Jet Propellant-8 or JP-8, a kerosene-based jet fuel that is used by the U.S. military in extreme conditions such as scorching deserts or subzero temperatures.

Converting this jet fuel into electricity is difficult using standard techniques because jet fuel contains sulfur, which can impair metal catalysts used to oxidize fuel in traditional fuel cells. The conversion process is also inefficient, with only 30 percent of the fuel converted to electricity under the best conditions.

To overcome these constraints, the Utah researchers used JP-8 in an enzymatic fuel cell, which uses JP-8 for fuel and enzymes as catalysts. Enzymes are proteins that can act as catalysts by speeding up chemical reactions. These fuel cells can operate at room temperature and can tolerate sulfur.

An enzyme «cascade» of two enzymes — alkane monooxygenase and alcohol oxidase — was used to catalyze JP-8. Hexane and octane, which are chemically similar to JP-8, also were tested as fuels. The researchers found that adding sulfur to their enzymatic fuel cell did not reduce power production.

«Enzymatic fuel cells are a newer type of fuel cell, so they are not currently on the market,» says Minteer, also a professor with USTAR, the Utah Science Technology and Research economic development initiative. «However, researchers haven’t been able to use JP-8 before, because they haven’t had the enzymes to be able to oxidize JP-8.»

Solid-oxide fuel cells at temperatures above 950 degrees Fahrenheit have made use of JP-8, but this is the first demonstration at room temperature, Minteer says. Now that the team has shown the enzyme catalysts works, they will focus on designing the fuel cell and improving its efficiency, she adds.

Minteer conducted the study with University of Utah postdoctoral researchers Michelle Rasmussen and Mary Arugula, and with Yevgenia Ulyanova, Erica Pinchon, Ulf Lindstrom and Sameer Singhal of CFD Research Corp. in Huntsville, Alabama.

This research was funded by Northrop Grumman Corp. and the National Science Foundation through the University of Utah’s Materials Research Science and Engineering Center.

The authors highlight the frail electrical power system of the ‘privileged’ West where it is taken for granted that there will be a continued stable supply of electricity for the distant future. Electrical power generation and distribution is more vulnerable than we might assume due to poor investment in infrastructure and many power grids operating close to capacity. Over the past 30 years, the demand for electricity has increased by 25%, while the construction of transmission faculties has fallen. It is argued that it will take large investments in electric utilities to meet future demand.

With our electrical infrastructures under threat, our dependence on electricity and our vulnerability when a blackout occurs are exposed; the economic damage of power outages and quality disturbances are estimated to cost the American economy between $25 and $180 billion per annum, although the indirect costs could be up to five times higher. Blackouts affect the economy and our everyday lives in a number of ways. Without electricity, food provisions are compromised as a lack of refrigeration means food cannot be stored safely, leading to increased risk of food poisoning; security systems fail and the crime rate increases, as it amplifies the opportunity for fraud, theft and exploitation. A lack of power also causes an immediate and prevalent problem for transport systems; traffic lights fail, rail systems come to a stop and air transport becomes compromised due to the loss of communications and unlit runways.

Despite a frail electrical infrastructure and the consequences of blackouts, our dependency on electricity continues to intensify, fuelled in part by consumer ‘addictions’ to electronic devices, air conditioning and, in the future electric vehicles. Electricity demands will become even greater as our resources become constrained due to the depletion of fossil fuel, a lack of renewable energy sources, peak oil and climate change. As we become more dependent on an uninterrupted supply of electricity for our comfort, security, communication systems, transport, health and food supply…what will happen when the lights go out?