Detection

Quantitative Carbon Detection

Utilization of carbonaceous feedstocks including petroleum, biomass, or waste for fuels leads to the complexity associated with large chemical mixtures comprised of thousands of organic compounds. For chemical analysis, each individual compound in the mixture must be separated, identified and quantified.  While separation (by chromatography) and identification (by mass spectrometry) has been achieved, quantification remains the primary challenge due to the need for individual molecular calibration.  In 2014, we developed a method called Quantitative Carbon Detection to eliminate the need for individual molecular calibration.  As depicted below, molecules eluting a gas chromatograph column pass through a PolyarcTM QCD microreactor where each analyte is fully combusted and then methanized in sequential microcatalytic chambers.  The resulting separated methane peaks are then quantified using Flame Ionization Detection.  This technique was commercialized by Activated Research Company, and the method was described in Lab on a Chip (2014).  Further applications were described for:  (a)  food, pharmaceuticals, and flavors in Analyst (2016), (b) hard to detect compounds such as CO2 or formaldehyde in RSC Analytical Methods (2017), and (c) for compounds that contain sulfur in AIChE Journal (2017)

GC System GC System with Polyarc QCDPolyarc and GC Housing

Zeolite Acid Site Titration by Reactive Gas Chromatography

Quantification of zeolite acid sites in common frameworks (BEA, Y, MFI, etc.) typically require complex instrumentation including ammonia or amine TPD, leading to limited application in the large field of zeolite catalysis.  Moreover, the complexity of conducting these TPD experiments can lead to variation in quantitative measurements due to interpretation or experimental repeatability.  In 2017, we developed a new technique for counting zeolite acid sites using a fully-automated gas chromatography.  Referred to as Reactive Gas Chromatography (RGC), this technique contains a zeolite sample within the inlet of a gas chromatograph.  The GC autosampler provides a pulse of amine in sequence until the zeolite is saturated.  Subsequent ramping of the temperature produces one reaction per acid site, which can be counted using a GC column and QCD-FID detector.  By this technique, acid site counting is simple, cheap, fast, automated and extremely sensitivie (~1.0 micro-mole/gram).  More information in Catalysis Science & Technology (2017).

Reactive Gas Chromatography