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Air purification of ammonia, a toxic industrial chemicals (TICs), by adsorption process on Metal-Organic Framework solids is attracting high scientific and commercial interests. While active carbon based adsorbents required high level of relative humidity for achieving proper performance ammonia capture, zeolite performance degrades in presence of humidity. For MOFs, the presence of humidity has been shown to be MOF dependent, either beneficial or detrimental. It appears that the role of humidity is of key importance and that different ammonia adsorption mechanisms co-exist depending on the material's physico-chemical features. Based on a screening of various microporous adsorbents including carbons, zeolites and MOFs, we show that in the presence of humidity, the ammonia uptake mostly follows the Henry law of ammonia solubilization in water. At the exception of Copper based MOF, the ammonia capture is mostly correlated with the amount of “condensed water” in the micropore. We also generally observe a systematic higher uptake than the Henry law which can be attributed to the effect of confinement i. e surface-condensed phase interaction. [ABSTRACT FROM AUTHOR]

Abstract: For economic and environmental reasons, there is a strong incentive to replace of homogeneous by green and efficient heterogeneous processes in catalysis. The Friedel-Crafts alkylation of aromatics is a marking example. Numbers of homogeneous catalysts (such as HF, H2SO3, and AlCl3) have been replaced by H-form zeolites. However, large pore zeolite can not accommodate bulk aromatic molecules and/or alkylating agents avoiding the reaction to take place within the porous network. Due to their larger pore size, metal-organic frameworks (MOFs) open the doors to the alkylation of very large poly-aromatic compounds. We report different approaches for the design of acid shape selective MOFs. The first refers to a “zeolite mimetic” approach. It deals with the design of porous Zn or Al based MOF exhibiting bridging –OH species (MOF-69, MIL-53 Al) like those found in zeolites [Si–O(H)–Al]. The second approach aims at synthesizing MOF materials having structural defects to generate active catalytic centers. Two different synthetic strategies were investigated, either by fast precipitation or by the partial substitution of dicarboxylic by mono-carboxylic acid linkers. Acid centers have been characterized by solid 1H NMR and Diffuse Reflectance IR. The mono-alkylation of biphenyl with tert-BuCl is achieved with 100% of para-selectivity, well superior to H-MOR and H-BEA reference zeolites. [Copyright &y& Elsevier]