seeing green

Houston lab develops reactor that sustainably turns waste into ammonia

Led by Haotian Wang (left) and Feng-Yang Chen, the Rice University team published a study this month detailing how its reactor system sustainably converts waste into ammonia. Photo by Jeff Fitlow/Rice University

A team of Rice University engineers has developed a reactor design that can decarbonize ammonia production, produce clean water and potentially have applications in further research into other eco-friendly chemical processes.

Led by Rice associate professor Haotian Wang, the team published a study this month in the journal Nature Catalysis that details how the new reactor system sustainably and efficiently converts nitrates (common pollutants found in industrial wastewater and agricultural runoff) into ammonia, according to the university. The research was supported by Rice and the National Science Foundation.

“Our findings suggest a new, greener method of addressing both water pollution and ammonia production, which could influence how industries and communities handle these challenges,” Wang says in a statement. “If we want to decarbonize the grid and reach net-zero goals by 2050, there is an urgent need to develop alternative ways to produce ammonia sustainably.”

Other methods of creating ammonia include the Haber-Bosh process and electrochemical synthesis. The Haber-Bosh process requires large-scale centralized infrastructure and high temperature and pressure conditions. Meanwhile, electrochemical synthesis requires a high concentration of additive chemicals.

According to Rice, the new reactor requires less additive chemicals than the electrochemical synthesis, allowing nitrates to be converted more sustainably. The reactor relies on an innovative porous solid electrolyte as well as recyclable ions and a three-chamber system to improve the reaction’s efficiency.

Additionally, this development provides an effective water decontamination method.

“We conducted experiments where we flowed nitrate-contaminated water through this reactor and measured the amount of ammonia produced and the purity of the treated water,” Feng-Yang Chen, a Rice graduate student who is the lead author on the study, says. “We discovered that our novel reactor system could turn nitrate-contaminated water into pure ammonia and clean water very efficiently, without the need for extra chemicals. In simple terms, you put wastewater in, and you get pure ammonia and purified water out.”

Pedro Alvarez, the George R. Brown Professor of Civil and Environmental Engineering, director of the Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment (NEWT) and the Water Technologies Entrepreneurship and Research (WaTER) Institute at Rice, says the reactor is "very timely and important" for growing cities that must deal with nitrate-contaminated groundwater supplies it.

"Conventional nitrate removal in drinking water treatment involves ion exchange or membrane filtration by reverse osmosis, which generates brines and transfers the nitrate problem from one phase to another,” he continues.

Wang's lab has been making headlines in recent years for innovative processes and technologies focused on the energy transition.

Last year, the lab published a study in Nature detailing a new technology that uses electricity to remove carbon dioxide from air capture to induce a water-and-oxygen-based electrochemical reaction, generating between 10 to 25 liters of high-purity carbon using only the power of a standard lightbulb.

In 2022, Rice reported that Wang’s lab in the George R. Brown School of Engineering had also replaced rare, expensive iridium with ruthenium, a more abundant precious metal, as the positive-electrode catalyst in a reactor that splits water into hydrogen and oxygen.

The lab received a portion of $10.8 million in research grants from the Houston-based Welch Foundation for research focused on converting carbon dioxide into useful chemicals, such as ethanol, last year. And Solidec, founded by Ryan Duchanois and Yang Xia from Wang's Lab, also received a $100,000 award from Rice as part of the One Small Step Grant program.

Wang has also been named among one of the most-cited researchers in the world.

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A View From HETI

Here are the 100 startups selected to participate in this year's Rice Alliance Energy Tech Venture Forum. Photo by Natalie Harms

The Rice Alliance for Technology and Entrepreneurship has named the 100 energy technology ventures that will convene next month at the 22nd annual Rice Alliance Energy Tech Venture Forum, as part of the second annual Houston Energy and Climate Startup Week.

Half of the startups, which hail from nine countries and 19 states, will pitch during the event, which culminates in the annual recognition of the “Most Promising Companies." The 12 companies that were named to Class 5 of the Rice Alliance Clean Energy Accelerator will present during Demo Day to wrap up their 10-week program.

In addition to pitches, the event will also host keynotes from Arjun Murti, partner of energy macro and policy at Veriten, and Susan Schofer, partner at HAX and chief science officer at SOSV. Panels will focus on corporate innovation and institutional venture capital. Attendees can also participate in one-on-one office hours with founders and investors.

The forum will take place Sept. 18 at Rice University’s Jones Graduate School of Business.

The 2025 presenting companies include:

  • Aeromine Technologies
  • AlumaPower
  • Ammobia
  • Aqua-Cell Energy
  • Aquafortus
  • Aquora Biosystems
  • Arculus Solutions
  • Artemis Production Solutions
  • AtmoSpark Technologies
  • AtoMe
  • Badwater Alchemy
  • C+UP
  • Carbon Blade
  • Circul8 Energy & Environment
  • CO2 Lock
  • Direct C
  • DirectH2
  • Ekona Power
  • Exum Instruments
  • Fathom Storage
  • Flyscan Systems
  • Geokiln Energy Innovation
  • Glint Solar
  • Hive Autonomy
  • Horne Technologies
  • Hydrogenious LOHC Maritime
  • Innowind Energy Solutions
  • Iron IQ
  • Kewazo
  • LiNova Energy
  • Lukera Energy
  • Lydian
  • Mcatalysis
  • Metal Light
  • Mithril Minerals
  • Moment Energy
  • Moonshot Hydrogen
  • Muon Vision
  • PolyQor
  • Polystyvert dba UpSolv
  • Precision Additive
  • RapiCure Solutions
  • Resollant
  • SiriNor
  • Skyven Technologies
  • Sperra
  • SpiroPak
  • Sweetch Energy
  • Teverra
  • Utility Global
  • Xplorobot

Companies participating in office hours include:

  • Active Surfaces
  • Advanced Reactor Technologies
  • Advanced Thermovoltaic Systems
  • Ai Driller
  • Airbridge
  • Airworks Compressors
  • Austere Environmental
  • Brint Tech
  • CarbonX Solutions
  • Cavern Energy Storage
  • Celadyne Technologies
  • CERT Systems
  • CubeNexus
  • Deep Anchor Solutions
  • Ellexco
  • Emerald Battery Labs
  • Equipt.ai
  • FAST Metals
  • FieldMesh
  • FlowCellutions
  • Fluidsdata
  • GrapheneTX
  • GS VORTEX SYSTEMS
  • Installer
  • Kanin Energy
  • MacroCycle Technologies
  • Modular MOPU
  • NANOBORNE
  • NetForwards
  • Oxylus Energy
  • PetroBricks
  • PHNXX
  • RASMAG Energy
  • RedShift Energy
  • RENASYS
  • RenewCO2
  • Resonantia Diagnostics
  • Respire Energy
  • Safety Radar
  • SeaStock
  • Secant Fuel
  • SolGrapH
  • Stratos Perception
  • Terraflow Energy
  • Think Energy Holdings
  • Turnover Labs
  • Utiltyx
  • Zenthos Energy

Find information about the full day of events here, or click here to register.

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