X-Ray Imaging of SAPO-34 Molecular Sieves at the Nanoscale: Influence of Steaming on the Methanol-to-Hydrocarbons Reaction

The effect of a severe steaming treatment on the physicochemical properties and catalytic performance of H-SAPO-34 molecular sieves during the methanol-to-hydrocarbons (MTH) reaction has been investigated with a combination of scanning transmission X-ray microscopy (STXM), catalytic testing, and bulk characterization techniques, including ammonia temperature programmed desorption and 27Al and 29Si magic angle spinning nuclear magnetic resonance. For this purpose, two samples, namely a calcined and a steamed H-SAPO-34 catalyst powder, have been compared. It has been found that calcined H-SAPO-34 displays a high selectivity towards light olefins, yet shows a poor stability as compared to a zeolite H-ZSM-5 catalyst. Moreover, in situ STXM at the carbon K-edge during the MTH reaction allows construction of nanoscale chemical maps of the hydrocarbon species formed within the H-SAPO-34 aggregates as a function of reaction time and steam post-treatment. It was found that there is an initial preferential formation of coke precursor species within the core of the H-SAPO-34 aggregates. For longer times on stream the formation of the coke precursor species is extended to the outer regions, progressively filling the entire H-SAPO-34 catalyst particle. In contrast, the hydrothermally treated H-SAPO-34 showed similar reaction selectivity, but decreased activity and catalyst stability with respect to its calcined counterpart. These variations in MTH performance are related to a faster and more homogeneous formation of coke precursor species filling up the entire steamed H-SAPO-34 catalyst particle. Finally, the chemical imaging capabilities of the STXM method at the Al and Si K-edge are illustrated by visualizing the silicon islands at the nanoscale before and after steaming H-SAPO-34.

Implementing the AIFMD: Success or failure? ECMI Commentary No. 34, 28 March 2013

This commentary considers the implementation of the Alternative Investment Fund Managers Directive (AIFMD) by the European Commission. The AIFMD creates an internal market for asset management and as an endeavour to develop market-based finance is an important piece of legislation for the European economy. The author, Mirzha de Manuel Aramendía, considers the implementation of some of the provisions that raised concern among industry participants. He finds that, on balance, a practical and flexible approach to implementation has been followed that should help secure the success of the framework, which at present is still uncertain. The commentary also considers the remuneration guidelines adopted recently by the European Securities and Markets Authority (ESMA). It encourages EU and national authorities to commit to the success of the AIFMD framework, as part of a broader effort to develop capital markets and reduce the historical reliance of the European economy on bank finance.