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Cu+-containing materials have drawn much attention in various applications because they are versatile, nontoxic, and low-cost. However, the difficulty of selective reduction and the poor stability of Cu+ species are now pretty much the agendas. Here, controlled construction of supported Cu+ sites in MIL-100(Fe) was realized under mild conditions (200 °C, 5 h) via a vapor-reduction strategy (VRS). Remarkably, the yield of Cu+ reaches 100%, which is quite higher than the traditional high-temperature autoreduction method with a yield less than 50% even at 700 °C for 12 h. More importantly, during the treatment via VRS some Fe3+ in MIL-100(Fe) are reduced to Fe2+, which prevent the frequently happened oxidation of Cu+ due to the higher oxidation potential of Fe2+. These properties make Cu+/MIL-100(Fe) efficient in the capture of typical aromatic sulfur, benzothiophene, with regard to both adsorption capacity and stability. To our knowledge, the stabilization of Cu+ using the oxidation tendency of supports is ...

Functionalization of metal–organic frameworks (MOFs) with Cu(I) sites is extremely desirable for various applications including adsorption, catalysis, and sensing. The traditional method for the conversion of supported Cu(II) to Cu(I) is high-temperature autoreduction (HTA), which produces Cu(I) with an unsatisfactory yield (ca. 50%) but requires quite harsh conditions (e.g. 700 °C, 12 h) that are unsuitable for MOFs. Here we report the rational design of an efficient, controllable strategy for the conversion of supported Cu(II) to Cu(I) by using vapor-induced selective reduction (VISR), in which vapors of weak reducing agents (e.g. methanol) diffuse into the pores of MOFs and interact with Cu(II) precursors. This strategy allows the fabrication of Cu(I) sites with a 100% yield without the formation of Cu(0) at much lower temperatures (e.g. 200 °C, 6 h) and subsequently preserves the structure of MOFs well. Due to the abundant Cu(I) sites and high porosity of MOF supports, the obtained materials exhibit excellent performance in adsorptive desulfurization with regard to capacity, selectivity, and recyclability.

Due to their versatility, nontoxicity, and low cost, Cu(I) ion exchanged zeolites are of great interest for various applications. Despite many attempts, the development of an efficient, controllable, and energy-saving approach to fabricate Cu(I) sites in zeolites remains an open question. In this study, a strategy was developed to convert Cu(II) in zeolites to Cu(I) selectively using vapor-induced reduction (VIR) with methanol. The methanol vapors generated at elevated temperatures diffuse into the pores of zeolites and interact with Cu(II) ions, leading to the formation of Cu(I). This strategy allows the construction of Cu(I) sites at low temperatures and avoids the formation of Cu(0). Moreover, the obtained material exhibits excellent performance in the adsorptive separation of propylene/propane with regard to both capacity and selectivity, which is obviously superior to the material prepared by the conventional autoreduction method as well as using various typical adsorbents.

Cu

Deep desulfurization of transportation fuels via π-complexation adsorption is an effective method for the selective capture of aromatic sulfur compounds. Taking into consideration that the desulfurization of transportation fuels proceeds in the liquid phase, separation and recycling of adsorbents should be greatly facilitated if the adsorbents were endowed with magnetism. In this paper, magnetically responsive core–shell π-complexation adsorbent microspheres, AgNO3/Fe3O4@mSiO2 (mSiO2 denotes mesoporous silica), which comprises a core of magnetite particles and a shell of mesoporous silica dispersed with AgNO3, was developed for the first time. The silica shell exhibits highly open mesopores with perpendicularly aligned pore channels, large surface area (694 m2 g−1) and uniform pore size (2.3 nm), which is quite beneficial to the accommodation of Ag(I) active species. As a result, AgNO3 can be well dispersed in the pores of silica shells and are highly accessible to adsorbate molecules. Our results show that the adsorbent is active in the adsorptive removal of a typical aromatic sulfur compound, thiophene, via π-complexation under ambient conditions. More importantly, the superparamagnetism allows the adsorbent to be separated conveniently from the adsorption system in several seconds by the use of an external field. After desulfurization, the adsorbents were regenerated by washing with isooctane and subsequent thermal dispersion in Ar. The regenerated adsorbent after six cycles still shows a good adsorption capacity (0.145 mmol g−1 or 4.64 mg g−1), which is comparable to the fresh adsorbent (0.147 mmol g−1 or 4.70 mg g−1). The magnetically responsive π-complexation adsorbent may be a promising candidate for the deep purification of transportation fuels.