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 achieved for the first time, which may offer a new idea to utilize active sites with weak stability.Keywords: adsorbents; desulfurization; metal−organic frameworks; stabilization; supported cuprous sites;

•The confined space hinders the aggregation of Au and retains the catalytic activity.•The SPR strategy avoids the competitive adsorption of solvent molecules with guests.•Highly dispersed Au species are highly active for catalytic reduction reactions.•The template favors the dispersion of Au and the enhancement of catalytic activity.Au-containing catalysts are highly active in diverse reactions, and their activity strongly depends on the dispersion degree of Au. Here we report for the first time a solid-phase reduction strategy to promote Au dispersion in template-occluded SBA-15 (AS) by fully considering three crucial factors, namely (i) the interaction between Au and supports, (ii) the space where Au precursors locate during reduction, and (iii) the reduction method. First, both template and silica walls in AS offer interaction with Au species. Second, AS presents confined spaces between template and silica walls. Third, the reduction in solid phase avoids the competitive adsorption of solvent molecules. The results show Au-containing AS has a better dispersion of Au than its counterpart prepared from template-free SBA-15 (CS). Moreover, the obtained materials exhibit excellent catalytic activity in reduction reactions and that the organic template retained in mesopores promotes the reactions greatly.Download high-res image (200KB)Download full-size image

Correction for ‘Smart adsorbents with reversible photo-regulated molecular switches for selective adsorption and efficient regeneration’ by Jing Zhu et al., Chem. Commun., 2016, 52, 11531–11534.

A new generation of smart adsorbents was designed by grafting photo-responsive molecules onto the pore entrances of mesoporous silica. These molecules act as the gates of the mesopores, which are reversibly closed/opened upon light irradiation. Our smart adsorbents thus realize both selective adsorption and efficient desorption, which is highly expected for adsorption but impossible for traditional adsorbents with fixed pore entrances.

Much attention has been paid to metal–organic frameworks (MOFs) due to their large surface areas, tunable functionality, and diverse structure. Nevertheless, most reported MOFs show poor hydrothermal stability, which seriously hinders their applications. Here a strategy is adopted to tailor the properties of MOFs by means of incorporating carboxyl-functionalized natural clay attapulgite (ATP) into HKUST-1, a well-known MOF. A new type of hybrid material was thus fabricated from the hybridization of HKUST-1 and ATP. Our results indicated that the hydrothermal stability of the MOFs as well as the catalytic performance was apparently improved. The frameworks of HKUST-1 were severely destroyed after hydrothermal treatment (hot water vapor, 60 °C), while that of the hybrid materials was maintained. For the hybrid materials containing 8.4 wt % of ATP, the surface area reached 1302 m2·g–1 and was even higher than that of pristine HKUST-1 (1245 m2·g–1). In the ring-opening of styrene oxide, the conversion reached 98.9% at only 20 min under catalysis from the hybrid material, which was obviously higher than that over pristine HKUST-1 (80.9%). Moreover, the hybrid materials showed excellent reusability and the catalytic activity was recoverable without loss after six cycles. Our materials provide promising candidates for heterogeneous catalysis owing to the good catalytic activity and reusability.

Silver (Ag)-based nanoparticles are one type of highly effective antimicrobial widely used in medical devices, consumer products, and wound dressing. Although Ag(I) rather than Ag(0) is the active species in antibacterial processes, the use of Ag(I) as antibacterial materials is hindered by its instability toward light irradiation. In this paper, we report the fabrication of core–shell AgCl@SiO2 nanoparticles, which comprise a core of AgCl nanoparticles and a shell of porous silica, for antibacterial applications for the first time. The porous silica shells not only enhance the stability of AgCl by preventing the core from direct light irradiation but also allow active Ag(I) to pass through continuously to inhibit the growth of bacteria. It is worth noting that the synthesis is achieved by a facile one-pot method in which the surfactant hexadecyltrimethylammonium chloride used for the formation of AgCl nanoparticles also acts as a structure-directing agent in the subsequent creation of porous silica. Our results show that the obtained AgCl@SiO2 nanoparticles exhibit well-defined core–shell structure and are highly efficient in the growth inhibition of Escherichia coli. More importantly, the stability of Ag(I) toward light irradiation is greatly enhanced by the protection of the silica shell. The convenient fabrication, well-defined core–shell structure, and enhanced stability make AgCl@SiO2 nanoparticles highly promising for antibacterial applications.Keywords: Antibacterial materials; Light stability; One-pot synthesis; Porous silica shell; Silver chloride nanoparticles

Elimination of aromatic sulfur and nitrogen compounds via selective adsorption is an effective method for the purification of transportation fuels to meet the increasingly stringent environmental requirements. Since the adsorption processes proceed in liquid phases, separation and recycling of adsorbents should be greatly facilitated if they were endowed with magnetism. In the present study, magnetically responsive core–shell microspheres, Fe3O4@C, which comprise a magnetite core and a carbon shell with a thickness adjustable from 47 to 97 nm, were fabricated for the adsorption of aromatic sulfur and nitrogen compounds. The carbon shell derived from the carbonization of a resorcinol–formaldehyde polymer possesses abundant porosity with a hierarchical structure, which is highly active in the capture of aromatic sulfur and nitrogen compounds despite the absence of any active metal sites such as Cu(I) and Ag(I). Our results show that the Fe3O4@C adsorbents with BET surface areas ranging from 227 to 264 m2 g–1 are capable of removing thiophene (0.483 mmol g–1), benzothiophene (0.476 mmol g–1), indole (0.463 mmol g–1), and quinolone (0.297 mmol g–1) efficiently under ambient conditions. More importantly, the superparamagnetism allows the adsorbents to be separated conveniently from the adsorption system by the use of an external field. The regenerated adsorbents after six cycles still exhibit a good adsorption capacity comparable to that of the fresh one. The present magnetically responsive core–shell Fe3O4@C adsorbents with low cost, high efficiency, and convenient recycling make them highly promising in the purification of transportation fuels.Keywords: Carbon; Core−shell microspheres; Denitrogenation; Desulfurization; Magnetically responsive adsorbents; Regeneration;

Fabrication of bifunctional Cu(I)/Ce(IV) sites in mesoporous silica SBA-15 requires a series of complicated steps, including introduction of the Ce(III) precursor, calcination to generate Ce(IV), further introduction of the Cu(II) precursor, and repeated calcination to generate Cu(I). This traditional method has low efficiency and wastes energy. Here we provide a highly efficient, convenient and green strategy for the fabrication of bifunctional Cu(I)/Ce(IV) sites in mesoporous silica SBA-15, for the first time. The precursors CuCl2 and CeCl3 were simultaneously introduced into SBA-15. Based on a guests-redox strategy, both the reduction of CuCl2 to CuCl and the oxidation of CeCl3 to CeO2 could be realized in one calcination step. This strategy avoids the repeated modification process, and guarantees a high Cu(I) yield of ∼59% without generation of toxic gas. In addition, the resultant materials show excellent performance in gas separation of C2H4 from C2H6.

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.

Metal–organic frameworks (MOFs) have attracted extensive attention due to their large surface area, diverse structures, and tuneable functionality. However, the poor hydrostability of most reported MOFs hinders their practical applications severely. In this paper, we report a strategy to modulate the properties of a typical MOF, namely MOF-5 [Zn4O(BDC)3; BDC = 1,4-benzenedicarboxylate] by hybridizing it with a natural clay (i.e. attapulgite), for the first time. A new kind of hybrid material resulting from the hybridization of the MOF and attapulgite was thus constructed. Our results showed that the hydrostability of the MOF was apparently improved due to the hybridization with attapulgite. The frameworks of MOF-5 were degraded seriously under the humid atmosphere, while the structure of the hybrid materials could be well preserved. We also demonstrated that the hybrid materials were highly active in the heterogeneous Friedel–Crafts alkylation reaction of benzyl bromide with toluene. The conversion of benzyl bromide reached ∼100% under the reaction conditions investigated. More importantly, the catalytic stability of the hybrid materials was significantly enhanced owing to the introduction of attapulgite. The activity could be well recovered with no detectable loss, and the conversion remained at ∼100% at the sixth run, which was apparently higher than that of MOF-5 (27.7% at the sixth run). The excellent hydrostability, catalytic activity, and reusability make the present materials highly promising for utilization as heterogeneous catalysts in practical applications.

Metal–organic frameworks (MOFs) show high potential in adsorptive removal of aromatic sulfur compounds; however, the crucial factors affecting the adsorption performances are scarcely clarified. In the present study, three classic aromatic sulfur compounds (i.e., thiophene, benzothiophene, and 4,6-dimethyldibenzothiophene) as well as five typical MOFs (i.e., MOF-5, HKUST-1, MIL-53(Fe), MIL-53(Cr), and MIL-101(Cr)) were selected for study. The adsorptive desulfurization performances of MOFs were investigated by using a fixed-bed adsorption system. In the case of thiophene, the adsorption capacity of MOFs decreases in the order MIL-53(Cr) > HKUST-1 > MOF-5 > MIL-53(Fe) > MIL-101(Cr). For the first time, the adsorbate–adsorbent interaction was examined in detail by using infrared spectra and temperature-programmed desorption. Such an interaction was demonstrated to be the most important factor affecting adsorption performance. When the molecular size of aromatic sulfur compounds is comparable to or smaller than the window diameter of MOFs, the influence of window diameter becomes apparent. It is surprising to find that the adsorbate–adsorbent interaction plays a major role, which is responsible for the poor adsorption performance of MIL-101(Cr) with quite high porosity. Therefore, metal sites and structure that contribute to the adsorbate–adsorbent interaction should be considered to be the most significant factor aiming to develop new MOFs for adsorptive desulfurization.

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.

Porous polymer networks have great potential in various applications including carbon capture. However, complex monomers and/or expensive catalysts are commonly used for their synthesis, which makes the process complicated, costly, and hard to scale up. Herein, we develop a molecular template strategy to fabricate new porous polymer networks by a simple nucleophilic substitution reaction of two low-cost monomers (i.e., chloromethylbenzene and ethylene diamine). The polymerization reactions can take place under mild conditions in the absence of any catalysts. The resultant materials are interconnected with secondary amines and show well-defined micropores due to the structure-directing role of solvent molecules. These properties make our materials highly efficient for selective CO2 capture, and unusually high CO2/N2 and CO2/CH4 selectivities are obtained. Furthermore, the adsorbents can be completely regenerated under mild conditions. Our materials may provide promising candidates for selective capture of CO2 from mixtures such as flue gas and natural gas.Keywords: CO2 capture; molecular template; porous polymer networks; regeneration; selectivity

This paper aims to improve the hydrothermal stability and catalytic activity of metal–organic frameworks (MOFs), which are believed to play an important role in the practical applications of MOFs in catalysis. Our strategy is to incorporate graphite oxide into a typical MOF, namely HKUST-1 (Cu3(BTC)2, BTC = 1,3,5-benzenetricarboxylic acid; HKUST = Hong Kong University of Science and Technology), and the properties of MOF are successfully tailored by use of this strategy. The obtained MOF/graphite oxide composites show enhanced porosity with high surface areas and some meso/macropores. For the composite containing 8.7 wt % of graphite oxide, the surface area reaches 1257 m2 g–1, which is obviously higher than pure HKUST-1 (841 m2 g–1). The pore structure of composites favors the access of reactant molecules to active sites and accelerates mass transfer in channels. Furthermore, the incorporation of graphite oxide creates a more hydrophobic environment surrounding metallic sites, which prevents the coordination bonds from attacking by water molecules and presents better affinity of active sites to organic reactants. Hence, the hydrothermal stability of MOF as well as the catalytic performance with regard to both activity and reaction rate are greatly improved. For the composite incorporating 8.7 wt % of graphite oxide, the conversion of styrene oxide in the ring-opening reaction can reach 74.1% after reaction for only 20 min, which is much higher than pure HKUST-1 (10.7%). More importantly, the catalytic activity can be well recovered without any loss even after six cycles. The excellent hydrothermal stability, catalytic activity, and reusability make our materials highly promising for use as heterogeneous catalysts in practical applications.

•DGC is developed to synthesize magnetically responsive MOF/Fe3O4 composites.•DGC simplifies synthetic procedures and minimizes solvent consumption.•The composites are used for adsorption desulfurization and denitrogenation.•The composites can be recycled efficiently by an external magnetic field.Selective adsorption by use of metal-organic frameworks (MOFs) is an effective method for purification of hydrocarbon fuels. In consideration that the adsorption processes proceed in liquid phases, separation and recycling of adsorbents should be greatly facilitated if MOFs were endowed with magnetism. In the present study, we reported for the first time a dry gel conversion (DGC) strategy to fabricate magnetically responsive MOFs as adsorbents for deep desulfurization and denitrogenation. The solvent is separated from the solid materials in the DGC strategy, and vapor is generated at elevated temperatures to induce the growth of MOFs around magnetic Fe3O4 nanoparticles. This strategy can greatly simplify the complicated procedures of the well-known layer-by-layer method and avoid the blockage of pores confronted by introducing magnetic Fe3O4 nanoparticles to the pores of MOFs. Our results show that the adsorbents are capable of efficiently removing aromatic sulfur and nitrogen compounds from model fuels, for example removing 0.62 mmol g−1 S and 0.89 mmol g−1 N of thiophene and indole, respectively. In addition, the adsorbents are facile to separate from liquid phases by use of an external field. After 6 cycles, the adsorbents still show a good adsorption capacity that is comparable to the fresh one.

Correction for ‘Smart adsorbents with reversible photo-regulated molecular switches for selective adsorption and efficient regeneration’ by Jing Zhu et al., Chem. Commun., 2016, 52, 11531–11534.

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.

Metal–organic frameworks (MOFs) have attracted extensive attention due to their large surface area, diverse structures, and tuneable functionality. However, the poor hydrostability of most reported MOFs hinders their practical applications severely. In this paper, we report a strategy to modulate the properties of a typical MOF, namely MOF-5 [Zn4O(BDC)3; BDC = 1,4-benzenedicarboxylate] by hybridizing it with a natural clay (i.e. attapulgite), for the first time. A new kind of hybrid material resulting from the hybridization of the MOF and attapulgite was thus constructed. Our results showed that the hydrostability of the MOF was apparently improved due to the hybridization with attapulgite. The frameworks of MOF-5 were degraded seriously under the humid atmosphere, while the structure of the hybrid materials could be well preserved. We also demonstrated that the hybrid materials were highly active in the heterogeneous Friedel–Crafts alkylation reaction of benzyl bromide with toluene. The conversion of benzyl bromide reached ∼100% under the reaction conditions investigated. More importantly, the catalytic stability of the hybrid materials was significantly enhanced owing to the introduction of attapulgite. The activity could be well recovered with no detectable loss, and the conversion remained at ∼100% at the sixth run, which was apparently higher than that of MOF-5 (27.7% at the sixth run). The excellent hydrostability, catalytic activity, and reusability make the present materials highly promising for utilization as heterogeneous catalysts in practical applications.

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.

A new generation of smart adsorbents was designed by grafting photo-responsive molecules onto the pore entrances of mesoporous silica. These molecules act as the gates of the mesopores, which are reversibly closed/opened upon light irradiation. Our smart adsorbents thus realize both selective adsorption and efficient desorption, which is highly expected for adsorption but impossible for traditional adsorbents with fixed pore entrances.