Superior resistance to alkali metal potassium of vanadium-based NH_(3)-SCR catalyst promoted by the solid superacid SO_(4)^(2-)-TiO_(2)

The significant decrease of acid sites caused by alkali metal poisoning is the major factor in the deactivation of commercial V_(2)O_(5)-WO_(3)/TiO_(2)NH_(3)-SCR catalysts.In this work,the solid superacid SO_(4)^(2-)-TiO_(2) modified by sulfate radicals,was selected as the catalyst support,which showed superior potassium resistance.The physicochemical properties and K-poisoning resistance of the V_(2)O_(5)-WO_(3)/SO_(4)^(2-)-TiO_(2)(VWSTi) catalyst were carried out by XRD,BET,H2-TPR,NH3-TPD,XPS,in situ DRIFTS and TG.The results pointed out that the introduction of SO_(4)^(2-)significantly increased the NH3-SCR catalytic activity at high temperatures,with an exceptionally high NO_(x) conversion over 90% between 275℃ and 500℃.When 0.5%(mass) K_(2)O was doped on the catalysts,the catalytic performance of the traditional V_(2)O_(5)-WO_(3)/TiO_(2)(VWTi) catalyst decreased significantly,while the VWSTi catalyst could still maintain a NOxconversion over 90%in the range of 300–500℃.The characterizations suggested that the support of SO_(4)^(2-)-TiO_(2) greatly increased the number of acidic sites,thereby enhancing the adsorption capacity of the reactant NH_(3).The results above demonstrated a potential approach to achieve superior potassium resistance for NH3-SCR catalysts using solid superacid.

Preparation,characterization and catalytic properties of S_2O_8^(2-)/ZrO_2-CeO_2 solid superacid catalyst

A novel solid superacid catalyst S2O8^2-/ZrO2-CeO2 was prepared by a coprecipitation method and characterized by means of XRD FTIR, BET, TEM and DSC/TG analysis methods. The results indicated that incorporation of appropriate amounts of Ce into the catalyst was beneficial to the formation of sole tetragonal ZrO2 and effectively prevented from the formation of monoclinic ZrO〉 and restrained the loss of sulfated species. XRD revealed the presence of tetragonal Ce0.16Zr0.84O2phase in the case of S2O8^2-/ZrO2-CeO2 calcined above 500 ℃. Catalytic activities of S2O8^2-/ZrO2-CeO2 for the esterification of lactic acid with n-butanol was studied. The results showed that the optimum conditions were as follows： calcination temperature of the catalyst 600 ℃, n（lactic acid）：n（n-butyl alcohol）=1.0：3.0, w（S2O8^2-/ZrO2- CeO2）=12.0%, reaction temperature 145 ℃, and reaction time 2 h. The esterification efficiency of lactic acid was about 96.6%.

Preparation of SO_4^(2-)/TiO_2-WO_3 solid superacid and its catalytic activity in acetalation and ketaltion

SO_4^(2-)/TiO_2-WO_3 was prepared and its catalytic activity under differentsynthetic conditions was discussed with esterification of n-butanoic acid and n-butyl alcohol asprobing reaction. The optimum conditions are found that the mass fraction of H_2WO_4 used in thecompound is 12.5 percent, the calcination temperature is 580 deg C, the calcination time is 3 h, andthe soaked consistency of H_2SO_4 is 1.0 mol centre dot L^(-1). Then SO_4^(2-)/TiO_2-WO_3 wasapplied as the catalyst in the catalytic synthesis of eight similar important ketals and acetalsunder the optimum conditions and revealed high catalytic activity. On condition that the molar ratioof aldehyde/ketone to glycol is 1:1.5, the mass fraction of the catalyst used in the reactants is0.5 percent, and the reaction time is 1.0 h, the yields of ketals and acetals can reach 64.2percent-95.1 percent. Moreover, it can be easily recovered and reused.

Preparation of SO_4^(2-)/TiO_2-MoO_3 Solid Superacid and Its Catalytic Activity in Acetalation and Ketalation

SO4^2-/TiO2-MoO3, a novel solid superacid, has been prepared and its catalytic activity at different synthetic conditions was examined with esterification of n-butanoic acid and n-butyl alcohol as probing reaction.The optimum conditions were also found, that is, the mass ratio of MoO3 used in the compound is 25%, the calcination temperature 450℃, and the soaked consistency of H2SO4 is 0.5mol.L^-1. Then it was applied in the catalytic synthesis of six similar important ketals and acetals as catalyst and revealed high catalytic activity. Under the condition that the molar ratio of aldehyde/ketone to glycol was 1:1.5, the mass ratio of the catalyst to the reactants was 0.5% and the reaction time 1.0 h, the yield of ketals and acetals reached up to 63.2%. The catalyst can be easily recovered and reused.

Preparation of SO_4^(2-)/TiO_2-La_2O_3 solid superacid and its catalytic activities in acetalation and ketalation

SO4^2- / TiO2-La2O3, a novel solid superacid, was prepared and its catalytic activities at different synthetic conditions are discussed with esterification of n-butanoic acid and n-butyl alcohol as probing reaction. The optimum conditions have also been found, mole ratio of n（La^3＋）：n（Ti^4＋） is 1：34, the soaked consistency of H2SO4 is 0.8 tool/L, the soaked time of HESO4 is 24 h, the calcining temperature is 480 ℃, the calcining time is 3 h. Then it was applied in the catalytic synthesis often important ketals and acetals as catalyst and revealed high catalytic activity. Under these conditions on which the molar ratio of aldehyde/ketone to glycol is l： 1.5, the mass ratio of the catalyst used in the reactants is 0.5%, and the reaction time is 1.0 h, the yields of ketals and acetals can reach 41.4%-95.8%.

Synthesis of Ethyl Oleate Catalyzed by Solid Superacid SO_4^(2-)/TiO_2/La^(3+)

Rare-earth compound solid superacid SO4^2 -/TiO2/La3＋ was prepared. Its catalytic activity was examined under different synthetic conditions for the esterification of propanoic acid and n-butyl alcohol as probing reaction. The optimum conditions were also found, which were the pH=8, the depositing time was 24 h, the mass fraction of La（NO3）3 used in solid superacid was 5%, the concentration of H2SO4 was 1.25 mol/L, the soaking time in H2SO4 was 16 h and the calcining temperature was 500℃. The ethyl oleate was synthesized from oleic acid and ethanol in the presence of SO4^2-/TiO2/La3＋. The optimum reaction conditions were obtained which were the reaction time was 6 h, molar ratio of oleic acid to ethanol was 1：4 and the mass fraction of catalyst was 4%.

Solid Superacid Catalyzed Efficient Synthesis of 2-Diethylaminoethyl Aryloxyacetates

Diethylaminoethyl aryloxyacetates are prepared efficiently in 75~95% yields bycondensation of the corresponding aryloxyacetic acids with 2-diethylaminoethanol in the presenceof catalytic amount of solid superacid SO4 /Fe2O3. 2-

An efficient synthesis of 2,2-bis(1H-indol-3-yl)-2H-acenaphthen-1-one catalyzed by recyclable solid superacid SO_4^(2-)/TiO_2 under grinding condition

An efficient synthesis of symmetrical 2,2-bis（1H-indol-3-yl）-2H-acenaphthen-1-one is achieved via a reaction of acenaphthe-nequinone and indoles catalyzed by solid superacid SO4^2-/TiO2 under solvent-free conditions at room temperature by grinding, which provides an efficient route to the synthesis of symmetrical 2,2-bis（1H-indol-3-yl）-2H-acenaphthen-1-one.This procedure offers several advantages including solvent-free conditions,excellent yields of products,simple work-up as well as reuse of catalysts which makes it a useful and attractive protocol for the synthesis of these compounds.

Alkylation of Isobutane and Butene on BrФnsted-Lewis Conjugated Solid Superacids

A BrOnsted-Lewis (B-L) conjugated solid superacid HPW-SbF_5/SiO_2 wassynthesized by a two-step method. This B-L acid shows high acid strength, high activity, goodselectivity and moderate stability in alkylation of isobutane/butene due to strong interactionbetween the BrOnsted acid and the Lewis acid, as confirmed by the results of IR, NMR and XPS. Undera mild reaction condition (30℃, 15-35xl0~5 Pa), the conversion of butene was maintained at 100% for110 hours on stream and the main products were C_8 and TMP. The results of alkylation conductedunder various operating conditions indicated that the activity was improved by increasing theloading content of HPW and SbF_5. The selectivity of TMP in the products was enhanced when theisobutane/butene ratio in the feedstock was increased. The existence of some intermediates was alsoreported.

Friedel-Crafts Acylation of Ferrocene Catalyzed by Solid Superacid,Silica-supported Polytrifluoromethanesulfosiloxane

Solid superacid, silica-supported polytrifluoromethanesulfosiloxane (SiO2-Si-SCF3) wasfirstly used in the Friedel-Crafts acylation of ferrocene as a novel catalyst. IR spectra, WAXD andspecific surface area of the superacid SiO2-Si-SCF3 were also investigated.

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℃ can be turned into superacid sites(with stronger acidity than that of 100%H2 SO4)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.

Catalytic Hydrothermal Liquefaction of Algae for Production of Bio-oil with Solid Superacid Catalyst SO_(4)^(2−)/ZrO_(2)

Solid superacid SO_(4)^(2−)/ZrO_(2)as heterogeneous catalyst was prepared to upgrade the bio-oil in the progress of hydrother-mal liquefaction(HTL)for the represented algae of Chlorella vulgaris and Enteromorpha prolifera.The solid superacid catalyst could obviously adjust the composition of the bio-oil and improve the higher heating values(HHVs).The catalytic performance could be regulated by adjusting the acid amount and acid strength of SO_(4)^(2−)/ZrO_(2).Furthermore,it was explored the catalytic effects of SO_(4)^(2−)/ZrO_(2)by the HTL for algae major model components,including polysaccharides,proteins,lipids,binary mixture and ternary mixture.The results showed that the introducing of SO_(4)^(2−)/ZrO_(2)catalyst could increase the yields of bio-oil from proteins and lipids,and avoid the Maillard reaction between polysaccharides and proteins.Moreover,a possible reaction pathway and mechanisms has proposed for the formation of bio-oils from HTL of algae catalyzed by SO_(4)^(2−)/ZrO_(2)based on the systematic research of the producing bio-oil from major model components.

Influence of Microwave Radiation on Properties and Structure of Fe_2O_3/SO_4^(2-) Solid Superacid Catalyst

The microwave radiation method was introduced to prepare the Fe_2O_3/SO solid superacid.Its structure and properties were investigated by means of X-ray diffraction and infrared spectrum analyses as well as measurement of magnetic susceptibility and rate of esterification. The structure of the superacids prepared in microwave field can be crystalline or non-crystalline, the latter has not been reported yet in literatures. Comparing with the traditional superacid, the non-crystalline Fe2O3/SO superacid prepared in microwave field has the highest magnetic susceptibility and catalytic activity. The di-coordination of Fe2O3 and SO and the S=O bi-bond were reinforced by microwave radiation, which is favorable for increasing the acid intensity of the Fe2O3/SO catalyst

Effect of Al Content on the Isomerization Performance of Solid Superacid Pd–S_2O_8^(2-)/ZrO_2–Al_2O_3

The effect of Al content on the performance of the Pd–S2O82-/Zr O2–Al2O3solid superacid catalyst was studied using n-pentane isomerization as a probe reaction. The catalysts were also characterized by X-ray diffraction(XRD), Fourier transform Infrared(FTIR), specific surface area measurements(BET), thermogravimetry–differential thermal analysis(TG–DTA), H2-temperature programmed reduction(TPR) and NH3temperature-programmed desorption(NH3-TPD). The Pd–S2O82-/Zr O2–Al2O3catalyst made from Al2O3 mass fraction of 2.5% exhibited the best performance and its catalytic activity increased by 44.0% compared with Pd–S2O82-/Zr O2. The isopentane yield reached64.3% at a temperature of 238 °C, a reaction pressure of 2.0 MPa, a space velocity of 1.0 h-1and a H2/n-pentane molar ratio of 4.0. No obvious catalyst deactivation was observed within 100 h.

ResearchonS202一／Zr02solidsuperacidinsynthesisofn—amylacetateundermicrowaveradiation

采用沉淀一浸渍法制得S2O62 8-／ZrO2固体超强酸，在微波辐射下催化合成乙酸正戊酯。通过单因素实验和正交实验优化了合成的反应条件；采用Hammett指示剂法、BET法、红外光谱、电子透镜技术和x_射线衍射对其进行了表征。实验结果表明，采用最佳制备条件下得到的催化剂在微波辐射下催化合成乙酸正戊酯的最优合成条件为：醇酸摩尔比1．9：1，反应温度135℃，反应时间25min，催化剂用量1．2g，功率500W，收率为97．8％。该工艺具有绿色、安全、操作简单和收率高等优点。

Hydroisomerization of n-Pentane over Zn-Fe-S2O8-2/ZrO2-Al2O3 Superacid Catalyst: Activity, Surface Analysis and the Investigation of Deactivation and Regeneration

The Zn and Fe modified /ZrO2-Al2O3 catalyst (Zn-Fe-SZA) was prepared and mechanisms of deactivation and methods for regeneration of as-prepared catalyst were explored with n-pentane isomerization as a probe reaction. The results indicated that the isopentane yield of the fresh Zn-Fe-SZA-F catalyst was about 57% at the beginning of the run, and declined gradually to 50% within 1500 min, then fell rapidly from 50% to 40% between 1500 and 2500 minutes. The deactivation of Zn-Fe-SZA catalyst may be caused by carbon formation on surface of the catalyst, sulfate group attenuation owing to reduction by hydrogen, removal of sulfur species and the loss of strong acid sites. It was found that the initial catalytic activity over Zn-Fe-SZA-T catalyst was 48%, which recovered by 84.3% as compared to that of fresh catalyst (57%). However, it showed a sharp decrease in isopentane yield from 48% to 29% within 1500 minutes, showing poor stability. This is associated to the loss of acidity caused by removal of sulfur species cannot be basically restored by thermal treatment. Resulfating the calcined catalyst could improve the acidity of catalyst significantly, especially strong acid sites, as compared with the calcined sample. The improved stability of the resulfated catalyst can be explained by: 1) eliminaton of carbon deposition to some extent by calcination process, 2) formation of improved acidic nature by re-sulfation, favoring isomerization on acidic sites, 3) restructuring of the acid and metal sites via the calcination-re-sulfation procedure.

Sulfated binary and trinary oxide solid superacids

A series of sulfated binary and trinary oxide solid superacids were prepared, and their catalytic activities for n-butane isomerization at low temperature were measured. The incorporation of different metal oxides into ZrO2 may produce a positive or negative effect on the acid strength and catalytic activity of the solid superacids. Sulfated oxides of Cr-Zr, Fe-Cr-Zr and Fe-V-Zr are 2 - 3 times more active than the reported sulfated Fe-Mn-Zr oxide. The enhancement in the superacidity and catalytic activity of these new solid superacids has been discussed on account of the results of various characteriation techniques.

Coke precursor as an intermediate during the alkylation of isobutane/butene over a solid superacid

Alkylation of isobutane/butene was conducted on a Br?nsted-Lewis conjugated solid superacid. It is found that some hydrocarbons accumulated on the catalyst surface. These hydrocarbons, as called coke precursor, played an intermediate role at the initial stage of the alkylation before they lead the catalyst to lose its activity. The presence of the intermediate is beneficial to the alkylation between isobutane and butene, while increase the TMP content and TMP/DMH ratio in the products

Preparation, Characterization of Superacid SO_4^(2-)/ZrO_2-SiO_2 and Its Activity on Catalytic Synthesis of Methyl p-Nitrobenzoate

Solid superacid SO42-/ZrO2-SiO2 was prepared by dip-impregnation method, and its catalytic activity was tested with esterification of p-nitrobenzoic acid and methanol. The optimum conditions were also found, that is, the molar ratio between silica and zirconia was 10：1, the calcination temperature was 550 ℃ and the soaked consistency of H2SO4 was 1.0 mol.L-1. Under the conditions that the ratio of methanol to aeid（mL/ g） was 12：1, the amount of catalyst was 0.5 g, the reaction time was 5 h and the stirring speed was 800 r.min-1, the yield of methyl p-nitrobenzoate could reach up to 90.5%. Then the characterizations of cataslyst, including the acidity and types of acidic centers, specific surface area and surface structure was respectively examined by Hammer indicator, in-situ pyridine IR, BET method, FT-IR（KBr）, transmission electron microscope （TEM）, and X-ray diffraction （XRD）. The results showed that the catalyst SO42-/ZrO2-SiO2 was superacid with high specific surface area due to Ho〈-12.70. It contained acidic sites of Lewis and BrФnsted, and its surface structure changed after esterification. The zirconia crystal was mainly tetragonal and silica crystal was not found.