Johnson Matthey Technology Review - Volume 65, Issue 2, 2021

Biofilms in industrial cooling tower systems are an important problem. The importance of the surface material in the response to an oxidising biocide (chloramine T trihydrate) was substantiated in our study. Polyvinyl chloride (PVC) cooling tower fill material, stainless steel cooling tower construction material and glass surfaces were compared by evaluating the bacterial loads on materials before and after biocidal treatment. The greatest logarithmic decrease in bacterial load was recorded as >3 log for glass after the first two months and for PVC after the second month. Actively respiring bacterial counts and adenosine triphosphate (ATP) measurements showed that there was no significant difference in the sensitivity of biofilm-associated cells to the biocide on the different surfaces. In addition, the effect of the biocidal treatment decreased with increasing biofilm age, regardless of the material.

The restructuring of the economy post-COVID-19 coupled to the drive towards Net Zero carbon dioxide emissions means we must rethink the way we use transport fuels. Fossil-carbon based fuels are ubiquitous in the transport sector, however there are alternative synthetic fuels that could be used as drop-in or replacement fuels. The main hurdles to achieving a transition to synthetic fuels are the limited availability of low-cost carbon dioxide at an appropriate purity, the availability of renewable hydrogen and, in the case of hydrocarbons, catalysts that are selective for small and particular chain lengths. In this paper we will consider some of the alternative fuels and methods that could reduce cost, both economically and environmentally. We recommend that increased effort in the rapid development of these fuels should be a priority in order to accelerate the possibility of achieving Net Zero without costly infrastructure changes. As ground transportation offers a more straightforward approach legislatively, we will look at oxygenated organic fuels as an alternative drop-in replacement for hydrocarbons.

The reduction of carbon dioxide into useful products such as fuels and chemicals is a topic of intense research activity at present, driven by the need to reduce atmospheric CO2 levels and avoid catastrophic temperature rises across the world. In this review, we consider a range of different technological approaches to CO2 conversion, their current status and the molecules which each approach is best suited to making. In Part I, the biological, catalytic and electrocatalytic routes are presented.

In this review, we consider a range of different technological approaches to carbon dioxide conversion, their current status and the molecules which each approach is best suited to making. Part II presents the photochemical, photoelectrochemical, plasma and microbial electrosynthetic routes to CO2 reduction and discusses the technological options together with proposals for future research needs from an industry perspective.

To combat the global problem of carbon dioxide emissions, hydrogen is the desired energy vector for the transition to environmentally benign fuel cell power. Water electrolysis (WE) is the major technology for sustainable hydrogen production. Despite the use of renewable solar and wind power as sources of electricity, one of the main barriers for the widespread implementation of WE is the scarcity and high cost of platinum group metals (pgms) that are used to catalyse the cathodic hydrogen evolution reaction (HER) and the anodic oxygen evolution reaction (OER). Hence, the critical pgm-based catalysts must be replaced with more sustainable alternatives for WE technologies to become commercially viable. This critical review describes the state-of-the-art pgm-free materials used in the WE application, with a major focus on phosphides and borides. Several emerging classes of HER and OER catalysts are reviewed and detailed structure–property correlations are comprehensively summarised. The influence of the crystallographic and electronic structures, morphology and bulk and surface chemistry of the catalysts on the activity towards OER and HER is discussed.

Microbial lipids hold great promise as biofuel precursors, and research efforts to convert such lipids to renewable diesel fuels have been increasing in recent years. In contrast to the numerous literature reviews on growing, characterising and extracting lipids from oleaginous microbes, and on converting vegetable oils to hydrocarbon fuels, this review aims to provide insight into aspects that are specific to hydroprocessing microbial lipids. While standard hydrotreating catalysts generally perform well with terrestrial oils, differences in lipid speciation and the presence of co-extracted compounds, such as chlorophyll and sterols, introduce additional complexities into the process for microbial lipids. Lipid cleanup steps can be introduced to produce suitable feedstocks for catalytic upgrading.

With the increasing demand for clean hydrogen production, both as a fuel and an indispensable reagent for chemical industries, acidic water electrolysis has attracted considerable attention in academic and industrial research. Iridium is a well-accepted active and corrosion-resistant component of catalysts for oxygen evolution reaction (OER). However, its scarcity demands breakthroughs in catalyst preparation technologies to ensure its most efficient utilisation. This minireview focusses on the wet-chemistry synthetic methods of the most active and (potentially) durable iridium catalysts for acidic OER, selected from the recent publications in the open literature. The catalysts are classified by their synthesis methods, with authors’ opinion on their practicality. The review may also guide the selection of the state-of-the-art iridium catalysts for benchmarking purposes.

Long-distance air travel requires fuel with a high specific energy and a high energy density. There are no viable alternatives to carbon-based fuels. Synthetic jet fuel from the Fischer-Tropsch (FT) process, employing sustainable feedstocks, is a potential low-carbon alternative. A number of synthetic fuel production routes have been developed, using a range of feedstocks including biomass, waste, hydrogen and captured carbon dioxide. We review three energy system models and find that many of these production routes are not represented. We examine the market share of synthetic fuels in each model in a scenario in which the Paris Agreement target is achieved. In 2050, it is cheaper to use conventional jet fuel coupled with a negative emissions technology than to produce sustainable synthetic fuels in the TIAM-UCL and UK TIMES models. However, the JRC-EU-TIMES model, which represents the most production routes, finds a substantial role for synthetic jet fuels, partly because underground CO2 storage is assumed limited. These scenarios demonstrate a strong link between synthetic fuels, carbon capture and storage (CCS) and negative emissions. Future model improvements include better representing blending limits for synthetic jet fuels to meet international fuel standards, reducing the costs of synthetic fuels and ensuring production routes are sustainable.

Shipping, which accounts for 2.6% of global carbon dioxide emissions, is urged to find clean energy solutions to decarbonise the industry and achieve the International Maritime Organization (IMO)’s greenhouse gas (GHG) emission targets by 2050. It is generally believed that hydrogen will play a vital role in enabling the use of renewable energy sources. However, issues related with hydrogen storage and distribution currently obstruct its implementation. Alternatively, an energy-carrier such as ammonia with its carbon neutral chemical formula, high energy density and established production, transportation and storage infrastructure could provide a practical short-term next generation power solution for maritime industry. This paper presents an overview of the state-of-the-art and emerging technologies for decarbonising shipping using ammonia as a fuel, covering general properties of ammonia, the current production technologies with an emphasis on green synthesis methods, onboard storage and ways to generate power from it.

This is Part II of an overview of the state-of-the-art and emerging technologies for decarbonising shipping using ammonia as a fuel. Part I (1) covered general properties of ammonia, the current production technologies with an emphasis on green synthesis methods, onboard storage and ways to generate power from it. The safety and environmental aspects, as well as challenges for the adaptation of technology to maritime structure, and an insight for the level of costs during fuel switching are now discussed to provide perspectives and a roadmap for future development of the technology.

The C123 project will develop two scenarios for the production of C3 products from unutilised natural gas sources. The add-on route targets propylene production in large, established petrochemical facilities. The modular route targets the production of a set of other C3 products from remote, stranded methane sources such as marginal gas or biogas. Potential sites for the exploitation of the C123 technology are investigated. A market study of the potential C3 products from the modular route, propanal, 1-propanol and propionic acid is then provided, which indicates that a smaller, local production process for these chemicals may have economic viability.

C123 is a €6.4 million European Horizon 2020 (H2020) integrated project running from 2019 to 2023, bringing together 11 partners from seven different European countries. There are large reserves of stranded natural gas waiting for a viable solution and smaller scale biogas opportunities offering methane feedstocks rich in carbon dioxide, for which utilisation can become an innovation advantage. C123 will evaluate how to best valorise these unexploited methane resources by an efficient and selective transformation into easy-to-transport liquids such as propanol and propanal that can be transformed further into propylene and fed into the US$6 billion polypropylene market. In C123 the selective transformation of methane to C3 hydrocarbons will be realised via a combination of oxidative conversion of methane (OCoM) and hydroformylation, including thorough smart process design and integration under industrially relevant conditions. All C123 technologies exist at TRL3 (TRL = technology readiness level), and the objectives of C123 will result in the further development of this technology to TRL5 with a great focus on the efficient overall integration of not only the reaction steps but also the required purification and separation steps, incorporating the relevant state-of-the-art engineering expertise.

A flexible combined heat, power and fuel production concept, FlexCHX, is being developed for managing the seasonal mismatch between solar energy supply and the demand for heat and power characteristic of northern and central Europe. The process produces an intermediate energy carrier (Fischer-Tropsch (FT) hydrocarbon product), which can be refined to transportation fuels using existing refineries. The FlexCHX process can be integrated into various combined heat and power (CHP) production systems, both industrial CHPs and communal district heating units. In the summer season, renewable fuels are produced from biomass and hydrogen; the hydrogen is produced from water via electrolysis that is driven by low-cost excess electricity from the grid. In the dark winter season, the plant is operated only with biomass in order to maximise the production of the much-needed heat, electricity and FT hydrocarbons. Most of the invested plant components are in full use throughout the year with only the electrolysis unit being operated seasonally. The catalytic reformer plays a key role in this process by converting tars and light hydrocarbon gases into synthesis gas (syngas) and by bringing the main gas constituents towards equilibrium. Developmental precious metal catalysts were used, and an optimal reformer concept was established and tested at pilot scale. Reforming results obtained at pilot gasification tests with commercial nickel catalysts and with the developed precious metal catalysts are presented.