In various industrial operations, gas, liquid, or ion separation typically relies on thermal processes. These methods exploit minor variations in boiling points to purify mixtures, consuming approximately 10% of the total energy in the United States.
MIT chemical engineer Zachary Smith aims to cut costs and lower carbon emissions by developing innovative filters that can effectively separate gases, liquids, and ions at room temperature, thereby replacing these energy-demanding techniques.
Within his MIT laboratory, Smith is constructing membranes featuring microscopic pores that can selectively filter minute molecules by size. These advanced membranes hold promise for applications such as purifying biogas, capturing carbon dioxide from power plant emissions, and facilitating hydrogen fuel production.
“We’re utilizing materials that offer unique capabilities for precise molecular and ionic separation, applying them to areas where existing methods are inefficient and contribute significantly to the carbon footprint,” explains Smith, an associate professor of chemical engineering.
Together with several of his former students, Smith has launched a company named Osmoses, dedicated to the large-scale development of these materials for gas purification. By eliminating the requirement for high temperatures in prevailing industrial processes, this technology could potentially decrease energy consumption by up to 90%.
“I envision a future where thermal separations are obsolete, and heat is no longer a barrier to producing the necessary goods and energy,” Smith comments.
Finding a Passion for Research
As a high school student, Smith was intrigued by engineering, despite lacking engineering role models—both his parents worked as physicians who encouraged academic diligence.
“I grew up without knowing many engineers, especially chemical engineers, yet I remained captivated by understanding how the world operates. My fascination with chemistry and how mathematics elucidates scientific principles led me to chemical engineering, although I was initially unaware of what it truly entailed,” recalls Smith, who grew up near Harrisburg, Pennsylvania.
At Penn State University, Smith collaborated with Professor Henry “Hank” Foley on a project that involved designing carbon-based materials to create a molecular sieve for gas separation. This intensive layering process eventually enabled him to develop a sieve capable of isolating oxygen and nitrogen from air.
“I kept layering a special material that I could later carbonize until selectivity was achieved. Ultimately, I created a membrane that could separate molecules differing by only 0.18 angstroms,” he shares. “At that moment, I became hooked on research, steering me toward further explorations in membrane technology.”
After graduating in 2008, Smith continued his academic journey at the University of Texas at Austin for graduate studies in chemical engineering, where he further developed membranes for gas separation using polymers. By manipulating polymer structures, he created films that filter specific molecules, including carbon dioxide and other gases.
“Polymers can be shaped into large devices compatible with state-of-the-art chemical plants, making it thrilling to discover this scalable material class that could truly address CO2 and energy-efficient separation challenges,” Smith states.
After earning his PhD, he pursued a postdoctoral fellowship at the University of California, Berkeley, to deepen his chemistry knowledge.
“I aimed to learn how to synthesize my own molecules and materials more systematically,” Smith explains.
During his time at Berkeley, he engaged in creating metal-organic frameworks (MOFs)—cage-like molecules with significant implications for gas separation and other disciplines. He soon recognized that while he appreciated chemistry, his true identity lay as a chemical engineer focused on practical applications.
“Through this experience, I learned much about chemistry and myself—though I enjoy collaborating with chemists, I am fundamentally a chemical engineer driven by process and application,” he asserts.
Tackling Global Issues
Smith’s recruitment to MIT was inspired by the distinctive mindset of its faculty and students.
“The remarkable talent of the people I met and their innovative approach differentiated MIT from other institutions. It wasn’t merely about advancing their field; they were creating entirely new domains. I found the ambition of those at MIT, who are committed to solving global challenges, truly inspiring,” he reflects.
In his MIT lab, Smith addresses global problems, including water purification, critical element recovery, renewable energy, battery development, and carbon sequestration.
Alongside Yan Xia, a Stanford University professor, Smith recently pioneered gas separation membranes that utilize a groundbreaking polymer type known as “ladder polymers,” which are currently being scaled for commercial use by his startup. Traditional polymer-based gas separation has faced limitations due to a balance between permeability and selectivity; membranes allowing rapid gas flow often lacked selectivity, letting impurities pass through.
The incorporation of ladder polymers—double strands interlinked by rung-like bonds—enabled the creation of gas separation membranes that are both highly permeable and exceptionally selective. This increased permeability—ranging from 100 to 1,000 times greater than previous materials—may allow these membranes to replace some traditional energy-intensive gas separation methods, according to Smith.
“This opens the door for envisioning substantial industrial challenges being addressed with compact devices,” he asserts. “By miniaturizing the system, our lab-developed solutions can easily transition to large industries like chemicals.”
Collectively, advancements made by Smith’s dedicated team, including students, postdocs, and collaborators, contribute to these innovative breakthroughs.
“I’m fortunate to lead a talented research team and teach subjects vital to my professional journey. MIT has been an incredible environment for exploration and discovery, and I am enthusiastic about our future findings as we tackle pressing global challenges,” Smith concludes.
Photo credit & article inspired by: Massachusetts Institute of Technology
