Frank S. Modica

Simple flow through reaction cells for in situ transmission and fluorescence x-ray-absorption spectroscopy of heterogeneous catalysts

We report on the design of both transmission and fluorescence x-ray-absorption spectroscopy cells suitable for in situ characterization of heterogeneous catalysts. The heart of both cells is a quartz tube used to house the catalyst sample. Both cells allow in situ x-ray-absorption fine-structure (XAFS) data to be recorded from -196 to 825 deg. C using a wide range of gas flows at atmospheric pressure. Excellent temperature control is demonstrated with both designs. XAFS data can be recorded over a wide x-ray energy range (2.1-29 keV). These designs are simple, robust, relatively low cost, and, moreover, are reliable and easy to operate. All of the critical components of the transmission reactor can be purchased commercially, with little machining required. The design of the fluorescence reactor requires access to a skilled glass blower.

Synthesis and catalytic activity of UZM-12

Abstract UZM-12 is a microporous crystalline aluminosilicate with ERI topology synthesized via the Charge Density Mismatch approach. The Charge Density Mismatch approach features synthesis from clear aluminosilicate solutions with high organic template content that are subsequently treated with crystallization inducing solutions. The solution containing low amounts of alkali and a higher charge density organic “crystallization” template, yields UZM-12 with Si/Al > 5.5 and nano- to micron-sized crystallites of spherical, plate or rod morphology depending on crystallization template, K + /Al ratio and synthesis conditions. Crystallization templates include the diquat-6, diquat-4, and benzyltrimethylammonium cations. The thermal, steam stability, and acid properties of H-UZM-12 were determined using the combinatorial heptane microreactor.

Design and Operation of an In Situ High Pressure Reaction Cell for X‐Ray Absorption Spectroscopy

The design and initial operation of an in situ catalysis reaction cell for x‐ray absorption spectroscopy measurements at high pressure is described. The design is based on an x‐ray transparent tube fabricated from beryllium. This forms a true plug flow reactor for catalysis studies. The reactor is coupled to a portable microprocessor‐controlled versatile feed system, and incorporates on‐line analysis of reaction products. XAFS data recorded during the reduction of a NiRe/carbon catalyst at 4 bar are used to illustrate the performance of the reactor.