Solid Superacid Research Articles

Catalytic hydroconversion of extraction residues from two Chinese lignites to arenes

A solid superacid TFMSA/MPZCA was prepared by impregnating trifluoromethanesulfonic acid (TFMSA) into mesoporous zirconia-coated attapulgite (MPZCA). Using TFMSA/MPZCA, the catalytic hydrocracking of coal-related model compounds (CRMCs) oxybis(methylene)dibenzene (OBMDB), benzyloxybenzene (BOB), and di(1-naphthyl)methane (DNM) and the catalytic hydroconversion (CHC) of extraction residues (ERs, isometric carbon disulfide/acetone-insoluble portion) from Huozhou lignite (HL) and Shaerhu lignite (SL) in cyclohexane without H2 were investigated. According to the model reactions, H+ released from TFMSA in TFMSA/MPZCA plays a crucial role in cleaving the > Calk-O- and > Car-C < bridged linkages (BLs) in the CRMCs, and the BLs of > Calk-O- in OBMDB and BOB can be completely cleaved at 170 °C and 190 °C for 3 h, respectively, while the BL of > Car-C < in DNM was not completely cleaved even at 320 °C. At 300 °C, the yields of soluble portions (SPs) from the CHC of HL- and SL-derived ERs significantly increase compared with the non-catalytic hydroconversion of both ERs. Arenes are predominantly abundant in the SPs from the CHC of both ERs and the most abundant compound in the SPs is mesitylene.

Accelerating Biodiesel Catalytic Production by Confined Activation of Methanol over High-Concentration Ionic Liquid-Grafted UiO-66 Solid Superacids

Solid acids usually show lower catalytic activities than liquid acids due to their limited acid strength and presence of obvious diffusion limitation in the reactions. We report herein a variety of...

Enhanced proton conductivities of chitosan-based membranes by inorganic solid superacid SO42−–TiO2 coated carbon nanotubes

To increase proton conductivity of chitosan (CS) based polymer electrolyte membranes, a novel nanofiller-solid superacide SO42--TiO2 (STi) coated carbon nanotubes (STi@CNTs) are introduced into CS matrix to fabricate membranes for polymer electrolyte membrane fuel cells (PEMFCs). Owing to the STi coating, the dispersion ability of CNTs and interfacial bonding are obviously improved, hence, CNTs can more fully play their reinforcing role, which makes the CS/STi@CNTs composite membranes exhibit better mechanical properties than that of pure CS membrane. More importantly, STi possesses excellent proton transport ability and may create facile proton transport channels in the membranes with the help of high aspect ratio of CNTs. Particularly, the CS/STi@CNTs-1 membrane (1 wt% STi@CNTs loading) obtains the highest proton conductivity of 4.2 × 10−2 S cm–1 at 80 °C, enhancing by 80% when compared with that of pure CS membrane. In addition, the STi@CNTs also confer the composite membranes low methanol crossover and outstanding cell performance. The maximum power density of the CS/STi@CNTs-1 membrane is 60.7 mW cm−2 (5 M methanol concentration, 70 °C), while pure CS membrane produces the peak power density of only 39.8 mW cm−2.

SO42-/SnO2 Solid Superacid Granular Stacked One-Dimensional Hollow Nanofiber for a Highly Conductive Proton-Exchange Membrane.

A novel sulfated tin oxide solid superacid granular stacked one-dimensional (1D) hollow nanofiber (SO42-/FSnO2) is proposed as a nanofiller in sulfonated poly(phthalazinone ether sulfone ketone) (SPPESK) to manipulate a highly conductive proton nanochannel. It has unique microstructures with an open-end hollow nanofibric morphology and grain-stacked single-layer mesoporous fiber wall, which greatly enlarge the specific surface area and aspect ratio. The diverse acid sites, that is, SO42-, Sn-OH Brönsted, and Sn4+ Lewis superacids, provide a high concentration of strong acidic proton carriers on the nanofiber surface and dynamically abundant hydrogen bonds for rapid proton transfer and interfacial interactions with -SO3H groups in the SPPESK along the 1D hollow nanofiber. As a result, long-range orientated ionic clusters are observed in the SO42-/FSnO2 incorporated membrane, leading to simultaneous enhancement of proton conductivity (226.7 mS/cm at 80 °C), mechanical stability (31.4 MPa for the hydrated membrane), fuel permeation resistance, and single-cell performance (936.5 and 147.3 mW/cm2 for H2/O2 and direct methanol fuel cells, respectively). The superior performance, as compared with that of the zero-dimensional nanoparticle-incorporated membrane, Nafion 115, and previously reported SPPESK-based membranes, suggests a great potential of elaborating superstructural 1D hollow nanofillers for highly conductive proton-exchange membranes.

Comparative study on flame retardancy of multiple solid super acids-containing epoxy resin composites

Five different solid superacids (SO42−/TiO2-MXOY), including SO42-/TiO2-CuO, SO42-/TiO2-ZrO2, SO42-/TiO2-Fe2O3, SO42-/TiO2-MnO, and SO42-/TiO2-MoO3, were successfully synthesized and characterized. Then, the fire retarded performance, smoke suppression and thermal stability of the epoxy resin (EP)/melamine coated ammonium polyphosphate (MAPP)/SO42−/TiO2-MXOY composites were investigated in details. The results showed that these SO42−/TiO2-MXOY can effectively enhance the limiting oxygen index (LOI) values of the EP/MAPP composites. Compared with that of the EP/MAPP composites, the total heat release (THR) values of the EP/MAPP/SO42−/TiO2-Fe2O3, EP/MAPP/SO42−/TiO2-ZrO2, EP/MAPP/SO42−/TiO2-MnO and EP/MAPP/SO42−/TiO2-MoO3 composites were remarkably reduced by 6%, 27 %, 32 % and 25 %, respectively, and the peak of heat release rate (PHRR) values of the EP/MAPP/SO42−/TiO2-Fe2O3, EP/MAPP/SO42−/TiO2-ZrO2, EP/MAPP/SO42−/TiO2-CuO, EP/MAPP/SO42−/TiO2-MnO and EP/MAPP/SO42−/TiO2-MoO3 composites were reduced by 0.3 %, 56.8 %, 23.6 %, 26.9 % and 36.9 %, respectively. Moreover, for the solid superacids-containing EP composites, the initial decomposition temperatures (Ti) and the temperatures at the maximum mass loss rate (TMax) were advanced, and the char yields at 800 °C were much increased, which was indicated the considerable effect on the thermal degradation and char formation. Hence, the MAPP and SO42−/TiO2-MXOY had good synergistic flame retardancy and smoke suppression, and the best for SO42−/TiO2-MnO.

Hydrodeoxygenation of Lignin‐Derived Monomers and Dimers over a Ru Supported Solid Super Acid Catalyst for Cycloalkane Production

AbstractThe monomers and dimers produced via lignin depolymerization are a promising alternative to transportation fuels after hydrodeoxygenation (HDO). However, these compounds contain numerous oxygen‐containing functional groups that are strongly bonded to aromatic rings. Therefore, the conventional HDO of lignin‐derived compounds faces serious problems of catalyst deactivation due to coke deposition and low hydrocarbon yields. A metal–solid super acid catalyst, i.e., Ru(SO42−)/ZrO2–CeO2, is synthesized, characterized, and evaluated for the HDO of various lignin‐derived monomers and dimers in a biphasic n‐dodecane/H2O system. A high cyclohexane yield of 98.5% is obtained by the HDO of phenol performed at 200 °C and 5 MPa. The “hydrated” configuration can be formed between the hydrogenation intermediates and H2O on the Ru sites. In addition, the anionic vacancies of ZrO2–CeO2 can be occupied by H− derived from the heterolytic cleavage of H2, leading to the formation of metal hydrides. The strong acidity of SO42−/ZrO2–CeO2 is beneficial for the subsequent deoxygenation of the hydrotreated products. In addition, the biphasic system can minimize the side reactions induced by the strong acidity of the catalyst. The catalytic system also exhibits a good catalytic performance for the HDO of other lignin‐derived monomers and dimers to produce cycloalkanes.

Improved flame resistance properties of unsaturated polyester resin with TiO2-M O solid superacid

Five SO 4 2− /TiO 2 -M X O Y solid super acids (SSA: Cu@Ti:SSA, Zr@Ti:SSA, Fe@Ti:SSA, Mn@Ti:SSA, Mo@Ti:SSA) were successfully prepared by sol–gel method, and its chemical structure and element content were characterized by X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FTIR) and energy dispersive spectroscopy (EDS). Then, a compound flame retardant system containing SSA and ammonium polyphosphate/montmorillonite (AM) were was introduced into an unsaturated polyester resin (UPR) to enhance the flame retardance. The effect of SSA on the flammability and thermal stability of the UPR was evaluated by the limiting oxygen index (LOI), cone calorimeter test (CCT) and thermogravimetric analysis (TGA). The LOI results showed that the flame retardance of the UPR composites was significantly improved with the addition of SSA. Moreover, their heat release rate (HRR), total heat release (THR), the smoke production rate (SPR) and CO and CO 2 yield were much decreased. In addition, the initial decomposition temperature of UPR/AM/SSA was delayed, indicating that their thermal stability was increased, and the residual char of UPR/AM/SSA was also increased due to strong catalytic of SSA ability for esterification and dehydration. Furthermore, the microstructure of the residual char after combustion of the UPR composites was studied by the scanning electron microscopy (SEM), and it was found that the char layer structure was more continuous and dense after the addition of the SSA. In sum up, the synergistic effect between SSA and AM was the main factor for the great improvement of flame retardant of UPR composites.

Catalytic Hydroconversion of Runbei Lignite over a Highly Active Solid Superacid

AbstractA highly active solid superacid, denoted as TFMSA/CNOFW, was prepared by calcining Ni‐organic framework (NOFW) to get calcined NOFW (CNOFW), into which trifluoromethanesulfonic acid (TFMSA) was impregnated. It was used to catalyze the hydroconversions of both oxybis(methylene)dibenzene (OBMDB) and the extraction residue (ERRL) from Runbei lignite (RL). The results show that over TFMSA/CNOFW, OBMDB was hydrocracked to toluene as the main product, indicating that TFMSA/CNOFW can heterolytically spit H2 to relatively mobile H+ and immobile H− attached on TFMSA/CNOFW. The addition of H+ to the oxygen atom (OA) in OBMDB produces phenylmethylium (PMI) and phenylmethanol (PMII). Toluene was yielded by the following 2 reactions: (1) the abstraction of H− by PMI from the TFMSA/CNOFW surface and (2) H+ addition to the OA in PMII, subsequent dehydration to form PMI, and the abstraction of H− by PMI from the TFMSA/CNOFW surface. In the similar mechanism, ERRL was hydrocracked to acetone‐soluble portion in the yield of 78.6% over TFMSA/CNOFW under 4 MPa of initial hydrogen pressure at 310 °C for 4 h.

Preparation of Biscuit-Like SO2-₄/ZrO₂ Catalyst for Alkylation of o-Xylene with Styrene.

We present here a facile synthesis of SO2-₄/ZrO₂ solid superacid by impregnating the biscuit-like mesoporous ZrO₂ nanoparticles prepared by an emulsion combustion method directly into H₂SO₄ solution. The obtained solid acid catalyst was characterized by means of X-ray powder diffraction, transmission and scanning electron microscopy, thermogravimetry, Brunner-Emmet-Teller measurement, and infrared analysis. Its catalytic performance was examined by alkylation of o-xylene with styrene. The optimal catalytic formulation, obtained from the investigation of experimental conditions, was determined to be 5 wt% of catalyst loading with initial o-xylene/styrene molar ratio of 5 under reaction temperature at 120 °C for 120 min, achieving a 100% styrene conversion and a 93.3% 1-phenyl-1-xylyl ethane selectivity. The biscuit-like SO2-₄/ZrO₂ solid acid exhibited high catalytic activity and selectivity and excellent structural stability. This synthetic strategy for preparing the mesoporous SO2-₄ promoted ZrO₂ solid superacid catalyst is generalized and expected to be applied to other metal oxides.

Catalytic removal of NO and dioxins over W-Zr-Ox/Ti-Ce-Mn-Ox from flue gas: Performance and mechanism study

Co-catalytic removal of multiple pollutants was able to reduce operating costs of enterprises, which was the main development direction for the waste incineration industry. In this work, series W-Zr-Ox/Ti-Ce-Mn-Ox (WZ/TCM) catalysts were designed to investigate independent NH3-SCR, dioxins oxidation and co-catalytic removal of NO and chlorobenzene (CB, the substitute of dioxins). The W-Zr-Ox mainly provided solid super acids; CeO2 and MnO2 enhanced the redox performance; and TiO2 provided a large specific surface area. All these factors guaranteed the excellent performance of WZ/TCM catalyst. The NO conversion of WZ/TCM reached 100 %, and the oxidation activity of CB was also higher than 85 % at 350–500 ℃. Meanwhile, the WZ/TCM had high N2 selectivity and excellent resistances to sulfur and water. In situ infrared diffuse reflectance spectra confirmed that ammonia gas mainly adsorbed on the Lewis acidic sites of the WZ/TCM catalyst and participated in the SCR reaction at low temperature. The ammonia species (NH4+) at the Brønsted sites participated in the reaction at high temperature. Furthermore, the chlorine atom on the chlorobenzene molecule was mainly removed to reduce toxicity when the oxidation of CB was at low temperature, which was deeply oxidized and had a variety of intermediate products at high temperature.

Catalytic microwave synthesis of biphenyl urea over mesoporous ZrO2-Al2O3

Solid acids such as ZrO2, Al2O3 and ZrO2-Al2O3 were prepared and analyzed for their physico-chemical properties like surface acidity and acid site distribution by NH3-TPD, crystalline nature by powder XRD, functionality by FT-IR, morphology by TEM and elemental analysis by ICP-OES methods. These solid acids were used as catalysts in the solvent free synthesis of biphenyl urea using microwave irradiation technique starting from aniline and dimethyl carbonate. Surface acidity and the phase of the solid acid were found to have a significant role in the synthesis of biphenyl urea. Up to (98%) yield of biphenyl urea with 100% selectivity was obtained in just 12 min. The activity of ZrO2-Al2O3 was compared with Mo(VI)/ZrO2 which is a solid super acid. For comparison, the reactions were also carried out by using conventional heating method. Kinetic studies were carried out to determine energy of activation of the solid acids. These solid acid catalysts were found to be reactivable and reusable when used for up to six reaction cycles.

An alumina‐coated UiO‐66 nanocrystalline solid superacid with high acid density as a catalyst for ethyl levulinate synthesis

AbstractBACKGROUNDThe zirconium‐containing metal–organic framework (MOF) UiO‐66 was used as a cell to synthesize SO42−/ZrO2@Al2O3, a high‐density superacid with relatively strong Brønsted acidity. The UiO‐66 MOF was first coated with alumina to form ZrO2@Al2O3. Impregnation with ammonium sulfate and calcination at 500 °C afforded the bimetallic composite solid superacid SO42−/ZrO2@Al2O3.RESULTSScanning and transmission electron microscopy images confirmed that UiO‐66 was successfully coated with aluminium oxide, and its octahedral structure and uniform size (400–600 nm) were retained. SO42−/ZrO2@Al2O3 had a Brunauer–Emmett–Teller specific surface area of 301–330 m2 g−1 and average pore diameter of 9.6–10.7 nm. X‐ray photoelectron spectroscopy and Fourier transform infrared analysis showed that SO42−/ZrO2@Al2O3 contained S6+ and Al3+. Temperature‐programmed ammonia desorption analysis showed that SO42−/ZrO2@Al2O3 contained super‐strong acid sites. The total volume of desorbed ammonia reached 90–109 cm3 g−1. Infrared spectra of adsorbed pyridine indicated that SO42−/ZrO2@Al2O3 contained mainly Lewis acid sites and was relatively rich in Brønsted acid sites. Thermogravimetric analysis showed that the thermal stability of SO42−/ZrO2@Al2O3 was high.CONCLUSIONSSO42−/ZrO2@Al2O3‐3M (the impregnation concentration of ammonium sulfate was 3 mol L−1) and glucose were used to synthesize ethyl levulinate (EL) in ethanol. The highest EL yield of 37.5 mol% was obtained after reacting the mixture at 200 °C for 5 h. An EL yield of 28.8 mol% was obtained after four consecutive reuses of the SO42−/ZrO2@Al2O3‐3M catalyst. © 2020 Society of Chemical Industry

Catalytic fast pyrolysis of biomass with Ni-P-MCM-41 to selectively produce levoglucosenone

Levoglucosenone (LGO) is a valuable chiral synthon and can be produced from pyrolysis of cellulose and biomass. In the present study, Ni-P-MCM-41 catalysts with various P-to-Ni ratios were prepared and employed for selective production of LGO from biomass. Both analytical pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and lab-scale experiments were conducted to explore the effects of several factors on the formation of LGO, including P-to-Ni ratio in Ni-P-MCM-41, catalyst/sample ratio and pyrolysis temperature. The results revealed that all the Ni-P-MCM-41 catalysts, especially the one with a P-to-Ni ratio of 5, exhibited excellent catalytic capability and selectivity for LGO production. For Py-GC/MS, the maximal LGO yields of 27.34 wt% and 14.30 wt% were achieved from cellulose and pine at 350 °C with catalyst/cellulose ratio of 3 and catalyst/pine ratio of 2, respectively. While in lab-scale experiments, the highest LGO yields from cellulose and pine were 21.37 wt% and 10.71 wt%, with the corresponding selectivity of 78.31% and 53.75%, respectively. The Ni-P-MCM-41 catalyst possessed much better catalytic efficiency on the LGO production than previously reported catalysts, including H2SO4, H3PO4, solid superacid, solid phosphoric acid and activated carbon.

The superior performance of dichloromethane oxidation over Ru doped sulfated TiO2 catalysts: synergistic effects of Ru dispersion and acidity

In this work, modified Ru/Ti catalysts with support sulfation by the introduction of solid superacid Ti(SO4)2 were employed for the catalytic combustion of dichloromethane (DCM). The experimental results showed that the optimal Ru/TiS0.05 sample yielded a near 100% DCM conversion at 275 °C, which was almost 30% higher than that of the pristine Ru/Ti catalyst. After a series of sample characterizations, it was found that there existed strong interactions between Ru species and sulfated TiO2 support, which would improve the dispersion of Ru species, thereby generating more active sites for DCM deep oxidation. Furthermore, the enhanced acidity derived from sulfation modification would facilitate DCM dissociation, and the generation of Brønsted acidic sites improved HCl selectivity. As such, both the enhancements in acidity and Ru dispersion after sulfation modification resulted in its superior performance of DCM catalytic abatement. Moreover, excessive Ti(SO4)2 addition would lead to the blockage of the pore structure and significantly decrease in the reducibility of the catalyst, leading to the loss of the activity.

Alkylation of isobutane with butene catalyzed by deep eutectic ionic liquids

The alkylation process of isobutane with butene is important in the petroleum industry. Ionic liquids (ILs) are considered as attractive alternative catalysts for isobutane alkylation besides strong liquid acids (H2SO4 or HF) and solid superacids. In this study, ILs based on amides-aluminum chloride (AlCl3) were synthesized and characterized, which exhibited both Lewis and Brønsted acidities. These deep eutectic ILs were found to be efficient catalysts for isobutane alkylation. The influences of the amide substrate, AlCl3/amide molar ratio, and metal additive on Lewis and Brønsted acidities were observed together with the synergetic effect of Lewis and Brønsted acid sites in the catalytic process. CuCl modified Urea-1.6AlCl3 showed the best catalytic performance. The butene conversion was about 99.9% and C8 selectivity reached 57.6% under optimized reaction conditions (temperature of 15 °C, stirring rate of 1500 rpm, hydrocarbon feeding rate of 300 mL/h, isobutane/olefin molar ratio of 15:1, and reaction time of 15 min). In addition, Urea-1.6AlCl3-0.13CuCl could be recycled and reused for at least 20 times without obvious loss in catalytic activity.

Fabrication of a solid superacid with temperature-regulated silica-isolated biochar nanosheets

This paper reports a new strategy for the structural reconstruction of biomass carbon sulfonic acid (BCSA) to its solid superacid counterpart. In this approach, a cheap layered biomass carbon (BC) source is chemically exfoliated by cetyltrimethyl ammonium bromide and then converted to silica-isolated carbon nanosheets (CNSs) by a series of conversion steps. The state of the silica-isolated CNSs and the stacking density of their nanoparticles are regulated by the dehydration temperature. Only the highly isolated and non-crosslinked CNSs with loose particle stacking structures obtained upon dehydration at 250 °C can be turned into superacid sites (with stronger acidity than that of 100% H2SO4) after sulfonation. This is accompanied by the creation of abundant hierarchical slit pores with high external surface area, mainly driven by the strong hydrogen bonding interactions between the introduced sulfonic acid groups. In typical acid-catalyzed esterification, etherification, and hydrolysis reactions, the newly formed superacid exhibits superior catalytic activity and stability compared to those of common BCSA and commercial Amberlyst-15 catalysts, owing to its good structural stability, highly exposed stable superacidic sites, and abundance of mesoporous/macroporous channels with excellent mass transfer rate. This groundbreaking work not only provides a novel strategy for fabricating bio-based solid superacids, but also overcomes the drawbacks of BCSA, i.e., unsatisfactory structural stability, acidity, and porosity.

Preparation, characterization, and application of ordered mesoporous S2O82−/ZrO2–SiO2 with high specific surface area

A series of ordered mesoporous S2O82−/ZrO2–SiO2 (OMSZS) solid superacids with different calcination temperatures (400–650 °C) was synthesized using zirconium n-propoxide and tetraethyl orthosilicate as the raw materials and P123 as a structure-directing agent by solvent evaporation-post-dipping method. Transmission electron microscopy and small-angle X-ray diffraction results showed that the OMSZS were all ordered. The nitrogen adsorption results indicated that the specific surface area of OMSZS could reach up to 331–385 m2/g, whereas the average pore diameters were in the range of 3.1–3.2 nm. The pyridine infrared results mainly displayed Lewis acids, and the ammonia (NH3)-temperature programmed desorption characterization showed that the NH3 desorption of the OMSZS calcined at 550 °C was 61 cm3/g STP. The catalytic performance of the OMSZS was investigated by the transesterification reaction of waste frying oil and methanol. The yield of fatty acid methyl ester could reach up to 94% at 200 °C reaction temperature for 6 h. After repeated use for four times, the catalyst still featured good activity and the yield was 78%.

Porous SiO2 coated AlxFeyZr1-x-yO2 solid superacid nanoparticles with negative charge for polyvinylidene fluoride (PVDF) membrane: Cleaning and partial desalinating seawater

In this work, porous SiO2 coated AlxFeyZr1-x-yO2 solid superacid nanoparticles with negative charge (CS-SAFZr) were synthesized via hydrolysis, sulfation and sulfonation, and characterized by SEM, TEM, XRD, BET and so on. The results show that the size of CS-SAFZr nanoparticles prepared under the optimum preparation conditions is around 80 nm, thickness of the porous SiO2 shell is about 20 nm, Hammett acidity is -16.197 and ion exchange capacity (IEC) is 0.98 mmol·g−1. Correspondingly, ferrum (Fe) and aluminum (Al) elements are successfully doped into the ZrO2 lattice and the doped nanoparticles present a specific surface area of 396.2 m2 g−1 with abundant hydroxyl and sulfonic acid groups on the surface. To investigate the properties of the nanoparticles as the filler, polyvinylidene fluoride (PVDF) was used as a candidate to prepare CS-SAFZr/PVDF ultrafiltration (UF) composite membranes and the performance were characterized via cleaning and desalinating seawater. Results indicate that the CS-SAFZr nanoparticles strengthen their compatibility with the membrane via hydrogen bonds and improve performances of PVDF membrane. The suspended solid and conductivity decline ratio of permeate seawater was 1.8 mg L−1 and 13.20% respectively, indicating that CS-SAFZr/PVDF membrane performs seawater cleaning and partial desalination. Therefore, CS-SAFZr nanoparticles can be a promising candidate to modify PVDF membrane for cleaning and desalinating seawater.

Preparation and characterisation of ordered mesoporous SO42−/Al2O3 and its catalytic activity in the conversion of furfuryl alcohol to ethyl levulinate

A series of ordered mesoporous SO42−/Al2O3 (OMSA) solid super acid catalysts were prepared by evaporation-induced self-assembly (EISA) method, followed by sulphonation at different calcination temperatures (400°C-900 °C). The results of transmission electron microscopy (TEM) and small-angle X-ray diffraction (XRD) indicated that all of the OMSAs possessed ordered mesoporous structures. The N2-Brunauer–Emmett–Teller (N2-BET) results showed that the specific surface area of OMSAs could reach up to 160–380 m2/g, and the average pore diameters fall into the range between 8.6 and 9.8 nm. The temperature-programmed desorption of ammonia (NH3-TPD) characterisation proofed that the OMSAs contained super acid, and ammonia desorption by the super acid in the OMSA calcined at 600 °C reached 25.9 cm3/g STP. The pyridine adsorption infrared (Py-IR) indicated that all of the OMSAs consisted mainly of Lewis acids. The OMSA was used to catalyse furfuryl alcohol in the synthesis of ethyl levulinate (EL). The maximum yield (80.6%) was obtained in the reaction conducted at 200 °C for 3 h. The reusability of the catalyst was proofed after four times of reuse as its activity was maintained with a yield of 71.2%.

Preparation and evaluation of degradable polyurethane with low surface energy for marine antifouling coating

Two polyurethanes were prepared through the reaction of 1,6-diisocyanatohexane (HDI) with two kinds of alcoholates. The first alcoholate was synthesized from alcoholized lactide (PLA) and dodecafluoroheptyl methacrylate (DFHMA) with the solid super acid (SO42−/ZrO) acting as the catalyst, and the other alcoholate was a mixture of PLA and DFHMA. The composition and structure of these two polyurethanes were investigated by infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The mass loss, attachment of bacteria and algae, and the water contact angle were used to evaluate the degradable and antifouling performance of the two polyurethane coatings. The results showed that the maximum contact angle of PLIPFI reached 129°, its mass loss was higher than 10% in 65 days, and after 65 days, the mass loss appeared to be stable, and the antiadhesion performance of the polyurethanes coatings was also enhanced. All of these results indicated that the PU modified with a graft segment may be promising for obtaining antifouling materials that not only can resist the adhesion of microorganisms but also show self-renewal.