Mesoporous Molecular Sieve SBA-15 Research Articles

Ultrasound-enhanced matrix solid-phase dispersion micro-extraction applying Mesoporous Molecular Sieve SBA-15 for the determination of multiple compounds in Fructus Psoraleae

An efficient ultrasound enhanced matrix solid-phase dispersion micro-extraction method was established for the extraction and determination of multiple ingredients (psoralenoside, isopsoralenoside, psoralen, isopsoralen, bavachin, psoralidin, isobavachalcone and bakuchiol) from Fructus Psoraleae applying ultra-high-performance liquid chromatography. The experimental factors affecting the extraction efficiency, including extraction solvent concentration, extraction solvent volume and ultrasound time, were optimized by the design of experiments methodology. Central composite design was applied in this optimization approach as a quadratic model. Under optimum conditions, good linear regression (r2 > 0.9999) and recovery (96.8%–104%, RSD<3.73%) for targets were attained. In addition, the intra-day of analytes was below 4.42% and inter-day precision of analytes was below 2.08%. This proposed method only required small amounts of reagent (0.5 mL) and materials usage (20 mg). Thus, the present study applied the efficient method to exhibit fast preparation and determination of eight ingredients of continents in Fructus Psoraleae.

Effect of additive on CuO-ZnO/SBA-15 catalytic performance of CO2 hydrogenation to methanol

AbstractThree kinds of porous catalysts CuO-ZnO/SBA-15 (CZ/SBA-15), CuO-ZnO-MnO2/SBA-15 (CZM/SBA-15) and CuO-ZnO-ZrO2/SBA-15 (CZZ/SBA-15) were synthesized by impregnation method with a siliceous framework mesoporous molecular sieve SBA-15. The performance of all catalysts for catalytic hydrogenation of CO2 to methanol was evaluated on a fixed bed reactor, combined with N2 adsorption-desorption (BET), X-ray diffraction (XRD), H2 temperature-programmed reduction (H2-TPR), temperature programmed desorption (H2-TPD, CO2-TPD), N2O titration, X-ray photoelectron spectroscopy (XPS) and transmission electron microscope (TEM) . The results show that the introduction of metal oxide in the catalyst changes the pore size and specific surface area of the SBA-15 molecular sieve support. The CuO-ZnO-MnO2/SBA-15 and CuO-ZnO-ZrO2/SBA-15 have high copper dispersion (DCu), large specific surface area (ACu), small surface CuO particle size, and easy to be reduced. Compared with the Mn-O cluster, the Zr-O cluster enhances the basic site and improves the methanol selectivity. In addition, CuO-ZnO-ZrO2/SBA-15 has the highest oxygen vacancy concentration and better catalytic activity among three catalysts. The methanol selectivity of CuO-ZnO-ZrO2/SBA-15 is 25.02%, which is 28% and 136.9% higher than those of CuO-ZnO/SBA-15 and CuO-ZnO-MnO2/SBA-15, respectively.

SBA-15 as a Support for Effective Olefin Metathesis Catalysts

Olefin metathesis is the catalytic transformation of olefinic substrates, finding a wide range of applications in organic synthesis. The mesoporous molecular sieve Santa Barbara Amorphous (SBA-15) has proven to be an excellent support for metathesis catalysts thanks to its regular mesoporous structure, high BET area, and large pore volume. A survey of catalysts consisting of (i) molybdenum and tungsten oxides on SBA-15, and (ii) molybdenum and ruthenium organometallic complexes (Schrock and Grubbs-type carbenes) on SBA-15 is provided together with their characterization and catalytic performance in various metathesis reactions. The comparison with catalysts based on other supports demonstrates the high quality of the mesoporous molecular sieve SBA-15 as an advanced catalyst support.

Synergistic Enhancement of CO2 Adsorption Capacity and Kinetics in Triethylenetetrammonium Nitrate Protic Ionic Liquid Functionalized SBA-15

A series of triethylenetetrammonium nitrate protic ionic liquid (TNPIL) functionalized, highly ordered mesoporous SBA-15 molecular sieves with different loadings have been synthesized via impregnat...

Synthesis of micro-mesoporous molecular sieve ZSM-5/SBA-15: tuning aluminium content for tert-butylation of phenol

Micro-mesoporous ZSM-5/SBA-15 molecular sieve was derived from mesoporous molecular sieves SBA-15 by hydrothermal crystallization approach. The silica-alumina ratio significantly affects the structure and catalytic performance of ZSM-5/SBA-15. When the $$\hbox {n}_{\mathrm{Si}}\hbox {/n}_{\mathrm{Al}}$$ is less than 25, the two-dimensional hexagonal pore structure of SBA-15 keeps intact with relatively low crystallinity of the pore wall. However, when the $$\hbox {n}_{\mathrm{Si}}\hbox {/n}_{\mathrm{Al}}$$ is larger than 50, the SBA-15 pores are severely damaged. When $$\hbox {n}_{\mathrm{Si}}\hbox {/n}_{\mathrm{Al}}$$ is 25, the catalyst ZSM-5/SBA-15 retains relatively good pore structure and shows excellent catalytic performance with 96.2% phenol conversion and 53.5% selectivity to 2,4-ditert-butyl phenol in the tert-butylation of phenol. SYNOPSIS Micro-mesoporous ZSM-5/SBA-15 molecular sieve was derived from mesoporous molecular sieve SBA-15 by hydrothermal crystallization approach. ZSM-5/SBA-15 ( $$\hbox {n}_{\mathrm{Si}}\hbox {/n}_{\mathrm{Al}}=25$$ ) retains relatively good pore structure and shows excellent catalytic performance with 96.2% phenol conversion and 53.5% selectivity to 2,4-ditert-butyl phenol in the tert-butylation of phenol. Effect of silica-alumina ratio of micro-mesoporous silica ZSM-5/SBA-15 on the catalytic performance of tert-butylation of phenol

The Construction of Sustained-Release Systems of Tanshinone IIA and Sodium Tanshinone IIA Sulfonate by SBA-15 Mesoporous Material.

The basic problems of the low dissolution rate of Tanshinone IIA (TSN) and the instability and precipitation of sodium tanshinone IIA sulfonate (STS) injection limit their usage in clinical. For these facts, the study aims to improve the dissolution rate of TSN and to enhance the sustained release effects of TSN and STS by using SBA-15 mesoporous molecular sieve as a drug carrier. Furthermore, controlling the pore size of SBA-15 and using different loaded methods to achieve expectations and provide a novel scheme for existing Danshen formulations. The effect of loading methods on drug loading efficiency (DL%), as well as the influence of the pore size of SBA-15s, the drug polarities and release mediums on drug loading and release behaviors were analyzed. It was found that the DL% was enhanced with the enlargement of the pore size, and was higher of TSN than STS. The in vitro tests of drug-loaded SBA-15s confirmed that the dissolution rate of TSN was improved obviously as compared with pure TSN. Moreover, SBA-15s prolonged the release times up to 12 h of TSN and 60 h of STS and promoted the sustained-release behaviors by decreasing the pore size. To ascertain the kinetic mechanisms of these samples, the Korsmeyer-Peppas release model was employed and the fitted results indicated that TSN/SBA-15s followed Fickian diffusion and non-Fickian transport was the predominant kinetic release mechanisms for STS/SBA-15s.

Study on the controlled synthesis and photocatalytic performance of rare earth Nd deposited on mesoporous TiO2 photocatalysts

Nanosized TiO2 photocatalysis technology is one of the most promising technologies for the treatment of wastewater containing azo dyes. In this work, TiO2 was deposited on a mesoporous SBA-15 molecular sieve by chemical deposition, and rare earth (RE) metal neodymium (Nd) was further deposited on the surface of the catalyst to obtain an Nd–TiO2–SBA-15 photocatalyst. The prepared photocatalyst was analyzed by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDS), and N2 adsorption–desorption. The activity of the Nd–TiO2–SBA-15 photocatalyst was evaluated by using methyl orange to represent the azo dye. The effects of different Nd deposition amounts and different solution pH values on the photocatalyst performance were principally studied. The results show that the synthesized photocatalyst formed an anatase crystal with a mesoporous structure. The specific surface area and pore size of the photocatalyst are 548.2 m2/g and 6.5 nm, respectively. As the amount of Nd deposition gradually increases, the activity of photocatalyst undergoes a process of first rising and then decreasing. In addition, the photocatalyst maintains high photocatalytic activity in the pH range of 2–10, exhibiting good acid–base adaptability. This work demonstrates that the Nd–TiO2–SBA–15 nanophotocatalyst has broad practical application prospects on a large scale.

Direct and postsynthesis of tin-incorporated SBA-15 functionalized with sulfonic acid for efficient biodiesel production

Two types of sulfonic acid functionalized tin-incorporated SBA-15 mesoporous molecular sieves catalysts were prepared by the post functionalization method and one-pot functionalization method, which were designated as p-Sn-SBA-15-SO3H and o-Sn-SBA-15-SO3H, respectively. The catalysts were characterized by X-ray diffraction, FT-IR, nitrogen adsorption-desorption, pyridine-FTIR, thermogravimetric analysis, scanning electronic microscope and energy dispersive X-ray spectroscopy. The results demonstrated that tin and sulfonic acid were introduced into the framework of SBA-15 successfully for both catalysts, the structure and morphology of p-Sn-SBA-15-SO3H was superiorto that of o-Sn-SBA-15-SO3H. However, the experimental results showed that o-Sn-SBA-15-SO3H revealed a higher catalytic activity (conversion of 97.9%) than p-Sn-SBA-15-SO3H (conversion of 93.2%), due to the higher acidity of o-Sn-SBA-15-SO3H. It can be inferred that the catalytic performance was relative to both the structure and acidity of the catalyst, but the latter was a main factor in the catalytic system. The o-Sn-SBA-15-SO3H catalyst could still retain over 85.0% of conversion after 6 reaction cycles, indicating its good reusability and possibility of industrial applications.

Preparation and Characterization of Highly Ordered Mercapto-Modified Bridged Silsesquioxane for Removing Ammonia-Nitrogen from Water.

In acidic conditions, mesoporous molecular sieves SBA-15 and SBA-15-SH were synthesized. Structural characterization was carried out by powder X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), 13C CP MAS-NMR, 29Si CP MAS-NMR and nitrogen adsorption–desorption (BET). The results showed that in SBA-15-SH, the direct synthesis method made the absorption peak intensity weaker than that of SBA-15, while the post-grafted peak intensity did not change. Their spectra were different due to the C-H stretching bands of Si-O-Si and propyl groups. But their structure was still evenly distributed and was still hexangular mesoporous structure. Their pore size increased, and the H-SBA-15-SH had larger pore size. The adsorption of ammonia-nitrogen by molecular sieve was affected by the relative pressure and the concentration of ammonia-nitrogen, in which the adsorption capacity of G-SBA-15-SH was the largest and the adsorption capacity of SBA-15 was the smallest.

Phosphotungstic acid immobilized on sulphonic-acid-functionalized SBA-15 as a stable catalyst for the esterification of cyclohexene with formic acid

Abstract Phosphotungstic acid (HPW) was immobilized on a sulphonic-acid-functionalized SBA-15 mesoporous molecular sieve through a one-step hydrothermal synthesis method, using non-ionic surfactant pluronic P123 as a structure-directing agent in acidic media, tetraethoxysilane (TEOS) as a silicon source and 3-trimethoxysilyl-1-propanethiol (MPTMS) with hydrogen peroxide (H2O2) oxidized to a sulfonic acid group. The obtained composite material HPW-SBA-15-SO3H has a high specific surface area, large pore volume and increased strong acidity. The effect of raw-material ratio on the catalyst was investigated. Catalysts that were prepared under optimal conditions of a molar ratio of (MPTMS)/ (MPTMS + TEOS) of 1:10, a molar ratio of (H2O2)/(MPTMS) of 18:1 and a mass ratio of (HPW)/(TEOS) of 1:10 exhibited an excellent catalytic activity in the esterification reaction of cyclohexene with formic acid. The cyclohexene conversion exceeded 86.7% and the cyclohexyl formate selectivity was 98.1% after 6 h at 353 K with a mole ratio of cyclohexene to formic acid of 1:3 and a catalyst dosage of 5.7% (w/w). The composite catalyst had a higher catalytic stability than the sulfonic-acid-functionalized SBA-15 and SBA-15-immobilized HPW individually. The cyclohexene conversion reached 72.0% even after reused four times. Fourier transform infrared and temperature-programmed desorption of ammonia revealed that a strong interaction existed between the sulfonic-acid group and the HPW, which prevented acid-active component of HPW and sulfonic-acid group loss from the carrier.

Preparation and photocatalytic application of magnetic Fe2O3/SBA-15 nanomaterials

Magnetic Fe2O3/SBA-15 mesoporous nanomaterials were synthesized by means of a facile impregnation and calcination method. As-prepared magnetic nanomaterials were characterized using XRD, N2 adsorption-desorption isotherms, SEM, TEM, VSM and XPS techniques. And the photocatalytic activities of magnetic Fe2O3/SBA-15 on the degradation of rhodamine B were also evaluated. Results indicate that the order structure of as-synthesized nanomaterials still remains, but its specific surface area, pore volume and pore size decrease. The saturation magnetization of the samples increases and its particle size decreases gradually with increasing the calcination temperature. And the existence of SBA-15 mesoporous molecular sieves increases largely the stability of γ-Fe2O3. Moreover, as-synthesized magnetic Fe2O3/SBA-15 shows high photocatalytic activities in the course of the degradation of rhodamine B by photo-Fenton-like reaction at natural pH about 6.3 and visible light irradiation. The structure and amount of catalyst, the concentration of H2O2 and rhodamine B are main influence factors on the degradation of rhodamine B, and these influence results have been depicted quantitatively from dynamics. Rhodamine B in aqueous solution could almost be removed completely after a period of illumination by visible light and overnight in the dark. Meanwhile, as-prepared magnetic Fe2O3/SBA-15 has excellent reusability and stability, which its photocatalytic activity has only a slightly decrease after five consecutive runs. Therefore, as-synthesized magnetic Fe2O3/SBA-15 has a broad prospect of practical application.

Pd and Pt nanoparticles supported on the mesoporous silica molecular sieve SBA-15 with enhanced activity and stability in catalytic bromate reduction

Bromate is a highly carcinogenic disinfection by-product in drinking water. Catalytic reduction is an emerging technology that can effectively remove bromate from water without forming additional brines and sludges. In this study, Pd and Pt nanoparticles supported on SBA-15 were prepared for catalytic bromate reduction. The activity investigation results showed that the Pt/SBA-15 catalysts exhibited higher activities than the Pd/SBA-15 catalysts and the commercial 5% Pd/C catalyst, and the highest catalytic activity of 24.72 mg·min−1·gcat−1 was obtained using 4% Pt/SBA-15 as the catalyst. This activity is approximately 2.33- and 6.50-fold higher than the activities of the 4% Pd/SBA-15 and 5% Pd/C catalysts, respectively. Analysis of the intrinsic mechanism revealed that the activation energy of bromate reduction over the 4% Pt/SBA-15 catalyst was 47.31 kJ·mol−1, and the reaction followed the Langmuir-Hinshelwood mechanism, suggesting that the reduction of adsorbed bromate on the Pt surface rather than the diffusion process controlled the overall reaction rate. Catalytic bromate reduction was strongly dependent on the reaction pH, and the catalytic activity increased with decreasing pH. Bromate reduction was suppressed in the presence of coexisting anions, including PO43−, SO42−, and Cl−, and the inhibition effects followed the order of PO43− > SO42− > Cl−. Surprisingly, bromate removal was obviously enhanced when a low concentration (<1.5 mM) of nitrate coexisted in the reaction solution. In addition, the losses in catalytic activity and Pt after five repeated tests were only 7.8% and 2.6%, respectively, revealing the high stability of the 4% Pt/SBA-15 catalyst in the catalytic reduction of bromate.

Adsorption-assistant detection of trace uranyl ion with high sensitivity and selectivity in the presence of SBA-15

A new strategy adsorption-assistant detection of trace uranyl ion is developed in this work employing fluorescence techniqe. Specifically, mesoporous molecular sieve SBA-15 is introduced in the process of determination of uranyl by esculin to enhance the sensitivity and selectivity. A linear detecting range of 0.001–0.05 μM and a limit of detection of 6 nM are achieved, which is probably due to the adsorption of both esculin and uranyl ion onto SBA-15. The KSV value is 8.69 × 106 mol−1 L, which was ca. 40 times of that without SBA-15.

Experimental research on purifying ultrafine nanoparticle by SBA-15 and its filtration mechanism

Airborne ultrafine nanoparticle (UFNP) is a key factor causing heavy haze pollution in Beijing-Tianjin-Hebei, which is very harmful to human health and the environment. Removal of environmental UFNPs by porous material is an important method of air purification treatment. However, the specific mechanism by which porous material filters UFNPs is not clear. In this study, UFNPs with 2–10 nm diameter were removed by SBA-15 mesoporous silica molecular sieves with different pore sizes, and the filtration mechanism was analyzed using transmission electron microscopy (TEM), specific surface area tests (BET), and X-ray photoelectron spectroscopy (XPS). The analyses showed a distinctive filtration of UFNPs over the interior mesopore channels. The removal efficiencies of SBA-15 with different pore sizes were also compared, demonstrating the influence of the pore size and structure on most penetrating particle size (MPPS). The UFNP filtration efficiency of SBA-15 increased with the increase of pore size. Moreover, SBA-15-14.6 could effectively purify UFNPs, and it had the highest fractional diffusive filtration efficiency of 98.79% and a total efficiency of 92.58% for UFNPs. This study provides a technical basis for the filtration of UFNPs using mesoporous materials.

Enhanced Nitrobenzene Adsorption in Aqueous Solution by Surface-Silanized Fly-Ash-Derived SBA-15

In this study, a two-step alkaline hydrothermal method was used to prepare SBA-15 mesoporous molecular sieves from fly ash obtained from a thermal power plant in Inner Mongolia, China. CH3O-SBA-15 was prepared using trimethoxychlorosilane as a modifier and toluene as the solvent. The silylated SBA-15 was characterized using X-ray diffraction, IR spectroscopy, N2 adsorption–desorption, and scanning and transmission electron microscopies. The adsorption of nitrobenzene (NB), a persistent organic hydrophobic pollutant, by silylated SBA-15 and improvements in its hydrophobicity were studied. The effects of adsorbent dosage, time, temperature, and pH on the NB adsorption rate were investigated. The results show that CH3O-SBA-15 has the same two-dimensional hexagonal pore structure as SBA-15 but that its specific surface area, average pore size, and pore volume are lower. The NB removal rate gradually increased with increasing adsorbent dosage and time. The NB removal rate gradually decreased with increasing te...

CO2 absorption and diffusion in ionic liquid [P66614][Triz] modified molecular sieves SBA-15 with various pore lengths

Mesoporous molecular sieves SBA-15 with four pore structures were loaded with an ionic liquid [P66614][Triz] to adsorb CO2 from raw biohythane. The hybrid sorbents of SBA-15 loaded with [P66614][Triz] were characterized by using N2 adsorption analyzer, thermogravimetric analyzer, scanning electron microscopy, and high-resolution transmission electron microscopy. The molecular sieve SBA-15 (with the most probable pore size of 4.3nm) loaded with 50% ionic liquid (IL), which was called SBA-15 (4.3) −50% IL, exhibited the fastest CO2 absorption rate and the shortest equilibrium time, which was approximately one-third of the equilibrium times of the other three hybrid sorbents. An intraparticle diffusion model was used to clarify that SBA-15 (4.3) −50% IL (with the shortest pore length of 120nm) executed a two-stage CO2 absorption process, which reduced the CO2 absorption time. The rate constant kI in the first stage of the CO2 absorption of SBA-15 (4.3) −50% IL was approximately four times as much as those of the other three hybrid sorbents because the cross-section area of its total pores was approximately three times higher than those of the other three hybrid sorbents. Results showed that pore length had significant effect on CO2 absorption performance.

Cerium Ions Grafted on Functionalized Mesoporous SBA-15 Molecular Sieves: Preparation and Its Catalytic Activity on p-Cresol Oxidation

Cerium ions were grafted onto the internal surface of organo-functionalized mesoporous SBA-15 molecular sieves by a post-synthesis method. The resultant SBA-DA-Ce materials were fully characterized by various analytical and spectroscopic techniques including powder XRD, N2 physisorption studies, SEM, FT-IR, DR-UV–Vis, TG-DTA, 29Si and 13C MAS-NMR techniques. The organo-functionality present on the surface was confirmed by the MAS-NMR and FT-IR studies, while the presence of cerium as Ce4+ ions was evident from the DR-UV–Vis studies. The catalytic activities of materials with different cerium ion content were assessed in terms of the oxidation of p-cresol under varying reaction conditions. The diamine-functionalized SBA-15 with 8 mmol of cerium ions per gram of SBA-15 (i.e., SBA-DA-Ce-8) showed the best catalytic activity, with a p-cresol conversion of ~ 87%. Cerium ions were grafted on the surface of functionalized SBA-15 by the post-synthesis method. The resultant SBA-DA-Ce showed promising activity on p-cresol oxidation with a conversion of 87%.

Immobilization of acetylcholinesterase on functionalized SBA-15 mesoporous molecular sieve for detection of organophosphorus and carbamate pesticide

The immobilization of acetylcholinesterase (AChE) on amino functionalized SBA-15 mesoporous sieves (NH2-SBA-15) was explored for detection of organophosphorus and carbamate pesticides. Several methods have been studied and the “adsorption-crosslinking” is found to be the best one. Firstly, AChE and bovine serum albumin (BSA) were adsorbed in turn on the surface of NH2-SBA-15 by electrostatic adsorption, and then glutaraldehyde was added for cross-linking the amino group of AChE. The NH2-SBA-15 showed around 95% immobilization efficiency and the specific activity of immobilized AChE (AChE-NH2-SBA-15) reached 130% relative to free AChE under optimal immobilization conditions. It was found AChE-NH2-SBA-15 retained 94.0% and 82.8% of its initial activity after 60days at 4°C and 25°C, respectively. It remained 55.0% of its initial activity after 6 times recycling. During the detection of pesticide, the AChE-NH2-SBA-15 showed wider linear range and much lower limit of detection compared with free AChE. The current method showed good recovery (93.8%-109.3%) and low RSD (<5%) for both standard solution and real vegetable samples of Carbaryl and Trichlorfon. It was believed that AChE-NH2-SBA-15 could be exploited as a fast, sensitive and low-cost biocatalyst towards the detection of pesticides residues which could be stored at room temperature for a long time.

Alkylation of phenol/ tert ‑butyl alcohol on ionic liquid-immobilized SBA-15 with different pore sizes

Mesoporous SBA-15 molecular sieves with different pore sizes were obtained using n-hexane as a micelle expander and NH4NO3 as structure adjuvant and used as support materials. The -SO3H immobilized environmentally Brӧnsted acidic ionic liquids were synthesized. Supported ionic liquids acid catalysts ([email protected] (5, 8, 12 nm)) were prepared by impregnation method and their physicochemical properties were characterized by FT-IR, TG-DSC, N2 physical adsorption, XRD, SEM and TEM. The catalytic activities of the synthesized acid catalysts were investigated by the alkylation of phenol with tert‑butyl alcohol (TBA). The effect of amount of IL supported, weight hour space velocity (WHSV), reactant mole ratio, reaction temperature, pore size of SBA-15 on the conversion of phenol and selectivity to products were investigated. Compared to [email protected] (5 nm) and [email protected] (12 nm), [email protected] (8 nm) exhibited the best phenol conversion up to 85.5% at 80 °C, suggesting that with the same content ionic liquid of catalysts, SBA-15 (8 nm) as support have remarkable catalytic activity and selectivity.

Metathesis of cardanol over ammonium tagged Hoveyda-Grubbs type catalyst supported on SBA-15

Cardanol (a mixture of phenols with C15 aliphatic unsaturated chain in meta position, manufactured from cashew nut shell liquids) is an abundant and till now practically waste natural material. An important way leading to its utilization as a renewable source of valuable phenolic compounds is represented by olefin metathesis.Quaternary ammonium tagged Ru complex of Hoveyda-Grubbs type immobilized on SBA-15 mesoporous molecular sieve by non-covalent interactions was proved as a very efficient catalyst for cardanol metathesis under mild conditions (35°C, toluene, 0.1 mol% of catalyst). The catalyst was used also in cross-metathesis of cardanol with alkenes (1-hexene, 1-heptene, 3-hexene, 4-octene) and unsaturated esters (methyl acrylate, 1,4-diacetoxybutene-2) under high yields of cross-metathesis products. The catalysts exhibited low leaching (from 0.2ppm to 2.9ppm Ru in products) and can be used in a continuous flow reactor (cumulative TON=2500).