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Tech Front: A New Way to Extract Hydrogen from Water

 

Hydrogen is considered an important source of clean energy, and the cleanest way to produce hydrogen gas is to split water into hydrogen and oxygen. But scientists have struggled to develop cost-effective water-splitting techniques.

Now, researchers at NC State University (Raleigh, NC) have created a technique using a new catalyst for converting methane and water into hydrogen and a fuel feedstock, called syngas, with the assistance of solar power. The team of chemical engineering researchers used a catalytic material that is more than three times more efficient at converting water to hydrogen gas than previous thermal-water-splitting methods.

“We’re excited about the new material and process because it converts water, inexpensive natural gas and clean, renewable solar energy into valuable syngas and hydrogen fuels,” said Feng He, a PhD student in the lab of Professor Fanxing Li at NC State and lead author of two articles describing the material and process.
Researchers at NC State developed a new catalytic compound that can be used to efficiently produce hydrogen and syngas.
Syngas is a mixture of carbon monoxide and hydrogen, and it’s used as a feedstock for commercial processes that produce synthetic diesel fuels, olefins, and methanol.

The technique hinges on a new catalytic material that is a composite of iron oxide and lanthanum strontium iron oxide, also known as LSF. Researchers have known that iron oxide can be used as a catalyst for thermal water splitting, but it is not very efficient. The addition of LSF significantly improves iron oxide’s activity, making it far more efficient. Using the new composite, the researchers were able to convert 77% of the water they used, in the form of steam, into hydrogen. The previous best conversion mark for thermal water-splitting was around 20%.

“We’re optimistic that commercial utilization of this technique could promote the efficient usage of solar energy and domestic natural gas, produce relatively low carbon dioxide emissions while making liquid transportation fuel, and generate low-cost, high-purity hydrogen,” he said.

The researchers’ new technique used methane injected into a reactor that is heated with solar energy. The chamber contains the catalytic composite, which reacts with the methane to produce syngas and carbon dioxide. This process “reduces” the composite particles, stripping them of oxygen. The syngas is removed from the system and the reduced composite particles are diverted into a second reactor. High-temperature steam is then pumped into the second reactor, where it reacts with the reduced composite particles to produce hydrogen gas that is at least 97% pure. This process also reoxygenates the composite particles, which can then be re-used with the methane, starting the cycle all over again.

The steam initially has to be produced with an external energy source, but once the cycle is initiated, the chemical reactions produce enough heat to convert water into steam without an external heat source. “We’ve created the catalytic particles and conducted every step of this process, but only in separate batches,” He said. “We’re now in the process of building a circulating bed reactor to operate this entire cycle in a continuous mode in real world conditions. Next steps include fine-tuning the catalytic compound to make it better and cheaper, improving the overall process, and developing better reactors.”

The work is described in two papers that were published in the Royal Society of Chemistry journal Energy & Environmental Science. “Perovskite promoted iron oxide for hybrid water-splitting and syngas generation with exceptional conversion” was published online Dec. 10, 2014, with He as lead author and his advisor, Fanxing Li, as senior author. An abstract for the paper is available at http://pubs.rsc.org/en/content/articlelanding/2015/ee/c4ee03431g#!divAbstract.
Schematic of the hybrid process for liquid fuel and hydrogen generation.
He and Li were also lead and senior author on “A hybrid solar-redox scheme for liquid fuel and hydrogen coproduction,” which was published online in April 2014. The April paper was also co-authored by Gregory Parsons of NC State, James Trainham of RTI, and John Newman of RTI and UC Berkeley. For an abstract of that paper, see http://pubs.rsc.org/en/content/articlelanding/2014/ee/c4ee00038b#!divAbstract. The work was supported by the National Science Foundation and the US Army Research Office.

 


SME Tech Papers: Learn More & Do More

Digital Depth

What’s in a word? Take “digital,” for example. We’ve come a long way from the Latin noun (digitus, meaning finger or toe) and adjective (digitalis) to a digital computer (added to the dictionary in 1947) and digitalizing (1962)/digitizing (1953) data or an image. Today’s younger generation knows mostly digital clocks, cameras and music.

All those 1’s and 0’s are increasingly a boon to manufacturing. The “digitization of equipment, processes, and organizations” is specifically cited in the definition of advanced manufacturing at www.manufacturing.gov. One of the institutes established in the US National Network for Manufacturing Innovation (NNMI) is the Chicago-based Digital Manufacturing and Design Innovation Institute (DMDII; dmdii.uilabs.org), with the mission to apply cutting-edge digital technologies to reduce the time and cost of manufacturing, strengthen the capabilities of the US supply chain and reduce acquisition costs. DMDII projects will be developed and deployed across key manufacturing industries.
Distributed process planning in a shared cyber workspace. From “A Review of Function Blocks for Process Planning and Control of Manufacturing Equipment,” L. Wang et al., Journal of Manufacturing Syste
SME Technical Papers document the path of the digital revolution, with “digital” as a search term calling up a range of papers from analog-to-digital conversions to digital techniques in automatic inspection (TP67PUB155) to direct digital manufacturing of functional products (TP13PUB4). “Smart”—as in “How to Add Smart Stuff to a Dumb Robot…” (TP84PUB439), “The Smart Foreman: Expert Systems for Manufacturing” (TP85PUB828) and “Smart Machining Systems…” (TP07PUB50)—and “cyber” are also relevant keywords.

The role of computers in decision-making, design and manufacturing is long established (TP68PUB63, TP67PUB193), for everything from welding parameter monitoring (TP75PUB54) and robot control (TP84PUB570) to optimizing grinding processes (TP90PUB293) and managing digital virtual factory objects (TP07PUB160).


Smarter All the Time

Smart processing and modeling, smart composites/fibers, smart cameras and smart tools have all come about through computer power taking “information about something that must be processed in order to be reacted to or acted upon” (TP68PUB63). Smart machining has brought intelligence “to improve process reliability, optimize machining performance and allow reliable unmanned operations” (TP04PUB365).

Tool condition monitoring combines information from a virtual CNC machine that is predicting the sensor output for a sharp tool with actual sensor data (TP04PUB333). Smart modeling enables incorporating desirable characteristics such as high flexibility, sharability and reusability (TP01PUB220).

Several papers from North American Manufacturing Research Conferences (NAMRC; www.sme.org/namrc) discuss smart machining systems. In 2006, authors M. Xu, C. Schuyler, R. Jerard and B. Fussell from the University of New Hampshire presented papers on cutting power model-sensor integration (TP06PUB58) and feedrate selection and tool condition monitoring (TP06PUB59) in a smart machining system to improve the efficiency of CNC machining. R. Ivester and J. Heigel presented a paper in 2007 on robust optimization and adaptive control optimization for turning operations (TP07PUB50).


Cyber Systems

As an abbreviated form of the word describing the automatic control of a process or operation (as in manufacturing) by means of computers (Webster’s Ninth New Collegiate Dictionary), “cyber” gets added to many other words for a high-tech, even futuristic, connotation. In 1985, cyber-based control systems provided “the very high degree of quality in addition to productivity” required for automated tube welding for aerospace applications (TP85PUB204), including post-weld reporting.

CyberCut, an experimental fabrication testbed for an Internet-accessible, computerized machining service, is described by UC-Berkeley’s Paul K. Wright and David A. Dornfeld in a 1996 paper published in the Journal of Manufacturing Systems (http://tinyurl.com/mkrertb), a 1998 NAMRC paper (TP98PUB156) and elsewhere. Wright’s earlier work on combining “powerful design and planning tools, supporting technical data, real time gauging and inspection, and hardware flexibility” in an open, self-sustaining system led to him receiving the 2007 NAMRI/SME S.M. Wu Research Implementation Award (www.sme.org/wu-award).

In NAMRC paper TP06PUB88, Malaysian authors describe a conceptual framework for a cyber manufacturing system for small and medium enterprises. The efficient optimization, management and productivity of digital virtual factories is presented in TP09PUB3, TP07PUB160 and TP07PUB182, the latter two from the International Conference on Comprehensive Product Realization (Beijing, June 2007). As described in TP07PUB160, “digital virtual manufacturing is a technology that can facilitate effective product development and agile production by using digital models representing the physical and logical schema and behavior of real manufacturing systems, including products, processes, manufacturing resources, and plants … to dramatically reduce the manufacturing preparation time and development costs for new products.”

TechFront is edited by Senior Editors Patrick Waurzyniak, pwaurzyniak@sme.org, and Ellen Kehoe, ekehoe@sme.org.

 

More than 16,000 papers make up SME’s knowledge collection. See search options for SME Technical Papers (coded as TP…PUB…) at http://tinyurl.com/SearchTPs.

Manufacturing practitioners are encouraged to send submissions for possible publication as SME Technical Papers. Contribute your knowledge to help people make things that improve our world! SME membership is not required. Learn more at www.sme.org/techpapers.

 

This article was first published in the May 2015 edition of Manufacturing Engineering magazine. Click here for PDF.   


Published Date : 2015-05-01

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