NETL Researchers Explore Applications for Unusual CO₂ Adsorbent

	Jeff Culp prepares an organic compound which will be used in the preparation of a metal organic framework material.
	Jeff Culp, a researcher at NETL, examines a sample of a dynamic metal organic framework material which may find applications in such technologies as gas purification, gas storage, and sensors.

NETL researchers have created a new adsorbent for carbon dioxide that shows very unusual behavior.

NETL is exploring possible applications of this unusual adsorption behavior in the areas of gas separation, gas purification, and in gas sensing devices.

The adsorbent is a flexible pillared-layer compound. It is one of a new class of materials, called metal organic framework or MOF.

The layers are sheets of an ionic nickel complex and the pillars are a specially selected organic compound. Together the sheets and pillars are inter-layered to form galleries of open channels in which gas molecules may be fit.

In the absence of carbon dioxide, the pillars are tilted and the structure is partially collapsed.  As carbon dioxide is adsorbed into this structure, the pillars lose their tilt and the structure opens to accommodate more gas molecules.

Most adsorbents that are used to capture gases have rigid structures that fill with increasing pressure and empty with decreasing pressure in a reversible way. When the new adsorbent is being filled with carbon dioxide, a certain threshold pressure of carbon dioxide is required to force the structure open.

Once the structure is full the pressure is released but the opened structure retains carbon dioxide until a very low pressure is reached.  As the carbon dioxide exits, the adsorbent returns to its previous collapsed structure.  The flexible nature of this structure depends on the exact structure of the pillar.

The achievement of this degree of control over the properties of a family of porous materials marks a real advance in adsorption science. A manuscript is being prepared for publication describing the results.

NETL Researchers Invent Mercury Detection Technology

	Researchers Evan Granite, left, and Henry Pennline have invented a technology to detect mercury in flue gases.

NETL inventors Evan Granite and Henry Pennline have added a mercury detection technology to their portfolio of several mercury removal technologies.

Their new invention detects mercury in flue gases, which will make it possible for power plants to verify that they are complying with regulations either issued or pending at the Federal level and in 26 states. NETL has applied for a patent.

The detection technology can be used with any mercury removal technology to determine how much mercury is present before the coal is burned and how much remains after combustion. The technology is a spinoff of the GP-254 removal technique which irradiates flue gas with ultraviolet light.

Pennline and Granite previously patented three mercury control technologies that have been licensed to industry for commercial use in removing mercury from coal-derived flue gases, including the GP-254 technique.

The new technique works by blending a small slipstream of hot flue gas with oxygen or air, and subsequently irradiating it with 254-nanometer ultraviolet light. Measuring the mercury in the resulting deposited mercuric oxide allows for the rapid determination of mercury concentration in the flue gas.

The United States Environmental Protection Agency recently issued a regulation for the reduction of mercury emissions from coal-burning utilities.  Twenty six states have legislation or pending legislation for mercury control on coal-fired power plants.

Mercury is present within coal-derived flue gases at infinitesimally small concentrations.  The typical concentration of mercury in untreated coal-derived flue gas is on the order of one part-per-billion, while treated flue gases often have sub part-per-billion mercury levels. 

The mercury in flue gas exists as elemental, oxidized, and particulate-bound forms.  The extraordinarily small concentrations, different mercury species, and the numerous reactive moieties present within flue gas complicate the determination of mercury.

NETL Researchers Pursue Gas Hydrates Across the Globe

	Kelly Rose of NETL’s Office of Research and Development examines sediment cores from the Indian Ocean aboard the drillship Joides Resolution.
	NETL’s Ray Boswell, right, and Tim Collett of USGS direct the sampling and analysis of gas hydrate bearing cores aboard the drillship Joides Resolution in the Indian Ocean.

Over the past 18 months, NETL researchers have pursued natural gas hydrates from India to Korea, from the Equator to the Arctic Circle.

Gas hydrates are solid combinations of natural gas and water that are found under Arctic permafrost and within the shallow sediments of deep-water continental shelves across the globe.

They have immense potential as a future energy resource and are also an important, yet poorly understood, component of the global carbon cycle and global climate change.

Kelly Rose of NETL is participating in the South Korean Methane Hydrates Expedition off the coast of Pusan, South Korea. She was invited by Geotek to participate as lead sedimentologist in the four-week expedition.

The goal of the South Korean expedition is to test pre-expedition exploration techniques for identifying the location and occurrence of sub-seafloor methane hydrate accumulations and fully characterize those accumulations through drilling and coring activities and subsequent analyses. 

Rose will be examining hydrate bearing and non-hydrate bearing core sub-samples in order to help characterize the features of these cores, and their relationships to one another and the other datasets gathered for this region.

In the summer of 2006, Rose and Ray Boswell of NETL logged more than 1,300 hours on the deck of the drilling vessel Joides Resolution offshore India serving as co-chief scientist and as project sedimentologist. The NETL researchers conducted 12-hour shifts leading the collection, description, and sub-sampling of gas hydrate-bearing sediment cores.

In February 2007, Boswell and Rose were joined by NETL’s Eilis Rosenbaum for a 22-day drilling and coring program on the Alaska North Slope. Team members guided sample selection and preservation, conducted the extraction and on-site geochemical analysis of pore waters from hydrate bearing reservoirs, and conducted unique experiments using an NETL-developed device to measure the changes in sediment thermal conductivity.

Earlier this year, Rose helped forge new international collaborations for DOE, participating as a project geologist for separate one-month expeditions in the South China Sea and Korea’s East Sea.

NETL scientists will continue to make critical contributions to projects that are advancing of the understanding of the occurrence, geological controls, and physical behavior of gas hydrates in nature.