4 new chemical technologies that could make an impact

Credit: Umicore

Researchers at Umicore's catalyst lab in Hanau, Germany.

Hydrogen is one of the fuels of the future. Hydrogen-powered fuel-cell vehicles emit no carbon dioxide, only a thin trail of water. Unlike electric cars, they can be refueled in minutes. And while H₂ is created mostly from methane today, proponents see a future when green hydrogen is generated cheaply by water electrolysis that uses energy from the wind and the sun.

But hydrogen is also an extremely light molecule that must be compressed for shipping and storage. The infrastructure to get it into fuel-cell vehicles or power plants exists in just a few places.

Umicore and Anglo American, two big players in precious metals, have formed an R&D venture to advance a novel solution to the compression problem: the liquid organic hydrogen carrier, or LOHC.

The idea behind the LOHC is to chemically bind hydrogen to a stable liquid carrier. This bound hydrogen can be loaded into a standard fuel tank just like a conventional liquid fuel, eliminating the need for compression, both in the fuel-loading lines and the vehicle itself.

For a hypothetical future vehicle to make use of the hydrogen, the hydrogen-loaded LOHC would pass through a reactor containing a dehydrogenation catalyst. Hydrogen would then be released and supplied to the fuel-cell stack of the vehicle, be it a car, truck, or train. The spent LOHC would be removed during the next fueling so it could be reloaded with more H₂.

Umicore and Anglo American formed their partnership in April, building on Anglo American’s earlier investment in Hydrogenious LOHC Technologies, a German LOHC start-up cofounded by Peter Wasserscheid, a chemist at Friedrich Alexander University Erlangen-Nuremberg. The partners’ focus is the dehydrogenation catalyst.

Some investors have warmed to the LOHC concept. In September, Hydrogenious LOHC raised close to $60 million from investors including Chevron to further develop LOHCs. The firm is building a test facility in Dormagen, Germany, where it will store hydrogen in an LOHC and test shipping it to customers.

Hydrogenious LOHC and Umicore agree that the best current LOHC candidate is benzyltoluene, owing to its combination of high heat capacity and storage density and low viscosity and surface tension. The molecule has long been an important heat-transfer fluid. In July, Hydrogenious LOHC signed an agreement to purchase benzyltoluene from Eastman Chemical, which makes it in Marl, Germany.

But Umicore and Anglo American say more work needs to be done on the catalyst that dehydrogenates the LOHC. In an April 26 online presentation to stock analysts to explain the research effort, An Steegen, Umicore’s chief technology officer at the time, said dehydrogenation with the current catalyst system requires pressures and temperatures too high to be practical for vehicle use.

Umicore’s role in the partnership is to develop a new heterogeneous catalyst—specifically, a precious metal fixed on an inorganic support material—that permits dehydrogenation at lower pressures and temperatures. The company cautions that the project is still at the early stages of development and that it will take 5–10 years before an efficient LOHC could be commercialized.

In the April 26 presentation, some analysts questioned the need for an alternative to compressed hydrogen for H₂ fuel systems. Alex Stewart of Barclays Investment Bank pointed out that “99% of the rest of the market is investing in the—sort of—old technology, which is getting pure hydrogen to the hydrogen fuel cells.”

And while the hydrogen vehicle market is nascent, it does exist in places such as California, which has 47 hydrogen fueling stations. Eric McFarland, chief technology officer of the carbon-free hydrogen start-up C-Zero, says he was once skeptical about filling a vehicle with compressed H₂. But McFarland has been driving the hydrogen-powered Toyota Mirai in California and says he’s become comfortable with the fueling process, which isn’t much different from a traditional gasoline fill-up.

Responding to Stewart, Steegen acknowledged that compressed hydrogen is the incumbent fuel-cell vehicle fuel. But she noted that the safeguards needed to make hydrogen-powered vehicles safe—sensors, alarms, special seals in the event of leakage, and a high-tech pressurized tank—add significantly to the vehicles’ cost.

Moreover, California’s experiment aside, converting the world’s existing fossil fuel transportation and storage infrastructure to hydrogen has yet to happen and would be a costly undertaking. Transitioning to a hydrogen-loaded LOHC would allow the existing infrastructure to stay mostly in place, Steegen said.

“That said,” she added, “LOHC is still in an early stage of development. We still need to work on the catalyst for dehydrogenation to make it compatible with onboard dehydrogenation. Also, the efficiency needs to improve. But nevertheless, it has the potential to basically be a very efficient hydrogen carrier towards the future.”

Credit: 09939-feature3-tanks.jpg

Refrigerant reclaimers carefully sort different gases and mixtures for recycling or destruction.

Fluorocarbons are tough, unreactive substances. That chemical stability is a big part of why they make such good refrigerants, foam-blowing agents, lubricants, sealants, and nonstick coatings. Once they’re installed, they resist breaking down or reacting with anything.

But the air conditioners and other products they are used in do break down, so the fluorocarbons often need to be destroyed. The Montreal Protocol on Substances That Deplete the Ozone Layer and the US Environmental Protection Agency have approved several destruction methods for refrigerants, mostly forms of high-temperature incineration.

A company called Midwest Refrigerants owns the only approved conversion method—one that consumes fluorocarbons and yields valuable chemical products.

Midwest isn’t an established chemical major, but it isn’t a conventional start-up either. Lew Steinberg and Doug Romine founded Midwest about a decade ago after retiring from careers in import-export and refrigerant reclamation. After seeing that the options for destroying fluorocarbons were expensive and often vented more greenhouse and ozone-depleting gases than they were supposed to, they worked with retired industrial fluorochemist Gregorio Tarancon III to develop and patent a better approach.

In the process they developed, hydrogen and carbon dioxide react with fluorocarbons at 600 to 900 °C over a blended transition-metal catalyst. It produces hydrogen fluoride, hydrogen chloride, and carbon monoxide as separate output streams. The exothermic reaction is self-sustaining once it gets going.

For example, hydrofluorocarbon-23 (HFC-23), a potent greenhouse gas with little commercial value, is an unavoidable by-product of making chlorodifluoromethane, commonly called R-22, an important polymer feedstock and fluorinating agent. The conventional solution, incinerating the HFC-23, costs about $6.50 per kilogram. Running the HFC-23 from a commercial R-22 plant through Midwest’s process would cost 60% less to do and would produce hydrogen fluoride and carbon monoxide worth millions of dollars per year, Steinberg says.

Including fees for taking the waste fluorocarbons and money made selling their end products, he says, Midwest can make around $5.50 for every kilogram of fluorocarbon it collects.

An attractive feature of Midwest’s technology is that it has no trouble with fluorocarbon blends. If a refrigerant is a single component, maybe contaminated with water or air, reclaimers can purify and re-sell it. But it’s often not economical to separate mixed fluorocarbons, so they are stored indefinitely or destroyed. Most new, low-global-warming-potential refrigerants are blends, so the demand for ways to deal with them at the end of a product’s life will only increase.

The technology also seems to work on another class of hard-to-destroy fluorochemicals: per- and polyfluoroalkyl substances (PFAS). Steinberg says Midwest has shown it can convert perfluorooctanoic acid, an environmentally persistent and widespread member of the PFAS family linked to a host of health issues, and it is testing other PFAS at its pilot plant in West Virginia.

Nirupam Aich, an assistant professor of environmental engineering at the University at Buffalo, says techniques for finding and isolating PFAS contamination are moving along nicely. “The major thing is to find how we can destroy the PFAS instead of just separating and removing it.” Aich is developing nanoparticles that can degrade certain PFAS and welcomes other approaches. “It’s not solvable by one single technology. Multiple disciplines have to come together, and multiple treatment technologies have to be combined.”

Steinberg and Romine want to install their plants on-site at the plants of customers, such as semiconductor makers, that need HF. Steinberg says Midwest can compete on price with conventional HF suppliers and eliminate the need to transport the highly reactive HF.

Transporting fluorocarbons, by contrast, is relatively simple, if “brutally detailed,” as Steinberg describes it. The most common challenge in the refrigerant reclamation supply chain is contamination or accidental mixing of refrigerants, which isn’t a problem for Midwest. “We take their screwups and turn it into money,” Steinberg says.

“From day 1, Midwest’s business model was to take end-of-life, unwanted refrigerants,” Steinberg says. As governments tighten regulations on refrigerants and other fluorocarbons, the volume of such materials that needs to be dealt with will grow. Introducing a new circularity—and profitability—to the equation could keep a lot of fluorocarbons out of the environment. “This will be our legacy,” Steinberg says.

Credit: Linde

Linde has operated a demonstration plant for Clariant's Edhox process in Pullach, Germany, since 2017.

Chemical companies want to reduce greenhouse gas emissions wherever they can, and one of their first targets is their most notorious source of carbon dioxide: the steam cracker.

Steam cracker furnaces burn massive amounts of natural gas and other hydrocarbons to achieve the temperatures of approximately 900 °C needed to break the carbon-hydrogen and carbon-carbon bonds in ethane, naphtha, and other feedstocks to make building-block chemicals like ethylene and propylene. Steam crackers emit around 1.2 metric tons (t) of CO₂ per 1 t of ethylene produced, according to a recent paper in Catalysts.

Many large petrochemical companies are greening their ethylene production. Dow, for instance, is building a cracker in Alberta that will capture its CO₂ for sequestration underground. For the longer term, the company, along with Shell Chemicals, is testing electric furnaces that would run on renewable power.

And many chemical companies are developing entirely new routes to ethylene. Among them are Clariant and Linde, which, in collaboration with the Technical University of Munich, have developed catalysts for an oxidative ethane dehydrogenation process that Linde calls Edhox. The companies say their process has the potential to eliminate 100% of the CO₂ emissions from ethylene production.

In the Edhox process, ethane reacts with oxygen to yield ethylene, water, and another commodity chemical, acetic acid.

The partners have been working on the technology for about 10 years, according to Marvin Estenfelder, global head of R&D at Clariant Catalysts. He notes that the development time for the process, now well advanced in the demonstration stage, isn’t particularly long for a “new-to-the-world process and a new-to-the-world catalyst.”

The companies had to overcome big technical hurdles over the past decade. One was combining oxygen and an alkane in a reactor without generating too many unwanted oxidative products, such as CO₂. The partners have managed to raise the selectivity of the catalysts to 93% for ethylene and acetic acid, minimizing CO₂ generation.

Another challenge was achieving adequate catalyst activity, essential for a commercially viable process. “In catalysis, you have a certain trade-off,” Estenfelder says. “If you push your catalyst to become more productive—more throughput through a certain volume of catalyst—you tend to deactivate the catalyst more quickly.”

Earlier this month, Clariant unveiled a catalyst, based on molybdenum and vanadium, for the system. These elements, which Clariant had been testing in the Edhox process since the beginning of the effort, have a long history in oxidation chemistry, Estenfelder points out. For example, molybdenum is employed in acrylonitrile and acrylic acid production. Vanadium-based catalysts are used in maleic anhydride production.

For the Edhox process, the partners had to keep the catalyst stable against phase changes that would deactivate it. Much of the development work went into the catalyst’s crystalline structure. The Clariant catalyst uses a proprietary promoter. Since the parties have been working together, they have increased productivity by nearly 70%.

The environmental advantages of the Edhox technology begin with the oxidation reactions themselves. Unlike endothermic ethane cracking, the oxidative dehydration of ethane is exothermic and occurs at temperatures below 400 °C, much lower than ethane cracking. The modest amount of CO₂ generated in the reaction is captured from the process gas in the separation section and is available in high concentration for downstream processing or sequestration, Estenfelder says.

Linde has been running the process in a demonstration unit in Pullach, Germany, since 2017. The unit uses a commercial-sized reactor tube of the kind already found in acrylic acid and maleic anhydride plants. It also has a molten-salt cooling system to moderate the temperature of the exothermic reaction and generate steam for the separation section of the plant.

Linde says it sees a fit for the technology with customers that might require ethylene and acetic acid. These include producers of vinyl acetate and polyethylene terephthalate. Since last October, Linde has also been collaborating with Shell, which had its own research in oxidative dehydrogenation.

Linde says it is in “discussion with potential clients” around the world, and it expects licenses in the coming years because of the industry’s “propensity to invest in sustainable petrochemical projects.”

Credit: Evonik Industries

Evonik Industries' Sepuran membranes use hollow fibers to separate gas streams and efficiently isolate helium.

Back in the day, when you drilled a well and gas came out, you’d set a match to it. If the plume caught fire, you started natural gas recovery. If not, you sealed it back up and moved on. But even when a gas reservoir doesn’t have enough hydrocarbons for drillers to make a profitable energy play, sometimes there’s helium in them there hills. Liter for liter, helium is worth at least 40 times as much as natural gas.

Most helium on the market today comes from wells that were drilled primarily for natural gas—methane in particular. The US Geological Survey recently estimated that the US has 8.7 billion m³ of helium that could be recovered profitably as a side product of natural gas extraction.

Despite that rosy number, the reality is that the global helium market has dealt with three major shortages since 2006 as well as many smaller ones going back even longer. Even now, technical problems at the US National Helium Reserve have forced gas companies to put some customers on helium rationing.

Seeing an opportunity, a growing number of pure-play helium start-ups are looking at those wells that are too small or too methane poor to make sense for conventional energy exploration. New membrane technology is making it profitable to open them up just for the helium. And Evonik Industries’ Sepuran Noble membrane is the leader of the pack.

Evonik developed Sepuran membranes in the first decade of this century. They come in cylindrical metal cartridges like most commercial membranes, but Sepuran uses closely packed hollow fibers instead of the more common rolled sheets.

The hollow fibers are made of a proprietary polyimide, explains Alex Evans, Evonik’s business development manager for Sepuran Noble in the Americas. Evonik’s first Sepuran membranes extracted methane from landfill- and wastewater-generated biogas. Evonik researchers optimized the extraction profile for helium, a noble gas, by tweaking the polymer, and Sepuran Noble was born.

Gases enter the cylinders on the inside of the hollow fibers and pass through to the spaces in between at different rates depending on their chemical identities. Water vapor is the first to pass through, followed by helium, hydrogen, and carbon dioxide in close succession. Further down the column, oxygen, carbon monoxide, nitrogen, and methane make their way across the membrane.

Depending on the mix of gases in the source stream and which ones a customer wants to collect, exit ports are placed at different spots along the column. Evans says the membranes can remove the vast majority of the non-helium components of the gas stream. Though both helium and carbon dioxide are usually present in the source gas and come off the column together, cold- or pressure-based separation methods can easily make the helium 99.999% pure—“five nines” in industry parlance—Evans says. The membranes can efficiently cut dilute helium streams down to a 50th or less in volume, he adds.

Large new helium projects could dampen interest in extracting helium from smaller wells. Gazprom just opened a massive new conventional helium plant in Amur, Russia. When the complex is fully operational in 2025, it will add 60 million m³ per year of helium to the global market. New supplies are also coming from Qatar and Australia.

But Phil Kornbluth, a helium consultant, says the Russian plant has already been struggling with shipping bottlenecks and other distribution problems. The troubles echo the decades of supply volatility that have bedeviled the helium industry and stressed out helium users.

“All of these supply chain issues are illustrating the value of having helium on the North American continent,” Kornbluth says. “Amur will definitely eventually loosen up the market, but it has to overcome these logistics bottlenecks before it has a really big impact.”

Kornbluth is cautiously optimistic that helium-focused extraction firms will succeed. “To the extent that people are building these small helium plants, there should be demand for Evonik’s membranes.”

The only commercial helium plant using Sepuran Noble today is a Linde operation in Saskatchewan. However, multiple new projects are in planning or construction phases, Evans says. He notes that the membranes are in use to recycle helium in fiber optics, leak detection, and spectroscopy.

The cost of Evonik’s modular system grows linearly with flow rate, Evans says, and the system has effectively no minimum size. At a facility the size of Amur, cryogenic separation is the cheapest way to get helium. But for a big chunk of the smaller end of the scale, Sepuran Noble offers lower capital and operational costs, Evans says. “I’m not necessarily trying to displace some of these larger cryogenic facilities. I’m trying to grow the circle of what wells are viable to produce helium.”