Thermal and catalytic upgrading of a biomass‐derived oil in a dual reaction system

The thermal and catalytic upgrsding of bio‐oil to liquid fuels was studied at atmospheric pressure in a dual reactor system over HZSM‐5, silica‐alumina and a mixed catalyst containing HZSM‐5 and silica‐alumina. This bio‐oil was produced by the rapid thermal processing of the maple wood. In this work, the intent was to improve the catalyst life. Therefore, the first reactor containing no catalyst facilitated thermal cracking of blo‐oil whereas the second reactor containing the desired catalyst upgraded the thermally cracked products. The effects of process variables such as reaction temperature (350°C to 410°C), space velocity (1.8 to 7.2 h^?1) and catalyst type on the amounts and quality of organic liquid product (OLP) were investigated, In the case of HZSM‐5 catalyst, the yield of OLP was maximum at 27.2 wt% whereas the selectivity for aromatic hydrocarbons was maximum at 83 wt%. The selectivities towards aromatics and aliphatic hydrocarbons were highest for mixed and silica‐alumina catalysts, respectively. In all catalyst cases, maximum OLP was produced at an optimum reaction temperature of 370°C in both reactors, and at higher space velocity. The gaseous product consisted of CO and CO₂, and C₁‐C₆ hydrocarbons, which amounted to about 20 to 30 wt% of bio‐oil. The catalysts were deactivated due to coking and were regenerated to achieve their original activity.     

Aqueous‐phase ketonization of acetic acid over Zr/Mn mixed oxides

Aqueous‐phase ketonization possesses significant advantages over gas‐ or organic‐phase ketonization for improved conversion efficiency of aqueous fraction accompanied by algal bio‐oil production. In this study, synthetized ZrO₂ and Zr/Mn oxides are used for aqueous‐phase ketonization of acetic acid. ZrMn_0.5O_x shows the highest ketonization activity at 340°C for 12 h, achieving maximum acetone yield of 88.27%; and all catalysts exhibited selectivity higher than 96.75%. Apparent activation energy and acid reaction order are 161.2 kJ mol^?1 and 0.70, respectively. Results suggest high ketonization activity of poorly crystallized tetragonal ZrO₂. Addition of Mn results in ZrO₂/MnO_x solid solution and improves active sites. Acid property and Mn⁴⁺ content are important factors, and oxygen vacancy demonstrates relationship with ketonization activity for ZrO₂. Examination of recovered catalysts indicates that ZrMn_yO_x exhibits improved stability, and Mn leaching and crystal phase transformation are main causes of deactivation in aqueous‐phase ketonization. © 2017 American Institute of Chemical Engineers AIChE J, 63: 2958–2967, 2017     

Converting Alkali Lignin to Biofuels over NiO/HZSM‐5 Catalysts Using a Two‐Stage Reactor

A series of NiO/HZSM‐5 catalysts were used to convert alkali lignin to hydrocarbon biofuels in a two‐stage catalytic pyrolysis system. The results indicated that all NiO/HZSM‐5 catalysts reduced the content of undesirable phenols, furans, and alcohols of the biofuel compared to non‐catalytic treatment. The NiO/HZSM‐5 catalyst with the lowest amount of NiO generated the highest biofuel yield in all catalytic treatments, and it also produced biofuel with the highest content of hydrocarbons. The emission of carbon oxides (CO and CO₂) increased in the treatments with higher‐NiO loading HZSM‐5 due to the redox reaction between NiO and the oxygenated compounds in the bio‐oil. Ni₂SiO₄ was generated in the used NiO/HZSM‐5 catalysts during the high‐temperature pyrolysis process.     

In situ analysis of volatiles obtained from the catalytic cracking of polyethylene

The effects of the solid‐acid‐catalyst pore size and acidity on polyethylene catalytic cracking were examined with a comparison of the temperature‐dependent volatile‐product‐slate changes when the polymer was cracked with HZSM‐5 and HY zeolites and the protonated form of MCM‐41. Volatile‐product distributions depended on the catalyst acidity and pore size. With HZSM‐5, paraffins were detected initially, and olefins were produced at somewhat higher temperatures. Aromatics were formed at temperatures 30–40°C higher than those required for olefin production. Small olefins (C₃–C₅) were the most abundant products when HZSM‐5 and MCM‐41 catalysts were employed for cracking polyethylene. In contrast, cracking with HY produced primarily paraffin volatile products (C₄–C₈). HY pores were large enough and the acid sites were strong enough to promote disproportionation reactions, which led to the formation of volatile paraffins. Compared with the other catalysts, HZSM‐5 with its smaller pores inhibited residue formation and facilitated the production of small alkyl aromatics. Volatile‐product variations could be rationalized by a consideration of the combined effects of catalyst acidity and pore size on carbenium ion reaction pathways. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3118–3125, 2001     

Effect of Gas Atmosphere on Catalytic Behaviour of Zirconia, Ceria and Ceria–Zirconia Catalysts in Valeric Acid Ketonization

Ketonization of valeric acid, which can be obtained by lignocellulosic biomass conversion, was carried out in a fixed bed flow reactor over ZrO₂, 5–20 % CeO₂/ZrO₂ and CeO₂ both under hydrogen and nitrogen stream at 628 K and atmospheric pressure. Regardless gas-carrier 10 wt% CeO₂/ZrO₂ was found to show higher catalytic activity compared to zirconia per se as well as other ceria modified zirconia while ceria per se exhibited very low catalytic activity. All catalysts provided higher acid conversion in H₂ than in N₂ whereas selectivity to 5-nonanone was insensitive to gas atmosphere. XRD, FTIR, UV–Vis DRS, XPS, HRTEM methods were applied to characterize catalysts in reduced and unreduced states simulating corresponding reaction conditions during acid ketonization. XRD did not reveal any changes in zirconia and ceria/zirconia lattice parameters as well as crystalline phase depending on gas atmosphere while insertion of ceria in zirconia caused notable increase in lattice parameter indicating some distortion of crystalline structure. According to XPS, FTIR and UV–Vis methods, the carrier gas was found to affect catalyst surface composition leading to alteration in Lewis acid sites ratio. Appearance of Zr³⁺ cations was observed on the ZrO₂ surface after hydrogen pretreatment whereas only Zr⁴⁺ cations were determined using nitrogen as a gas-carrier. These changes of catalyst’s surface cation composition affected corresponding activity in ketonization probably being crucial for reaction mechanism involving metal cations catalytic centers for acid adsorption and COO^? stabilization at the initial step.     

Hydrogenation of dimethyl oxalate to ethylene glycol over mesoporous Cu‐MCM‐41 catalysts

The synthesis and utilization of mesoporous Cu‐MCM‐41 catalysts for hydrogenation of dimethyl oxalate to ethylene glycol is described in this article. Physicochemical properties of these Cu‐MCM‐41 catalysts have been investigated by N₂‐physisorption, X‐ray diffraction, inductively coupled plasma, N₂O titration, transmission electron microscopy, temperature programmed reduction, Fourier transform infrared spectroscopy, and X‐ray photoelectron spectroscopy. It was found that the copper loading significantly influenced the pore structure and copper surface area of the catalyst. High catalytic performance is obtained over a 20Cu‐MCM‐41 catalyst with a full DMO conversion and EG yield of 92% at a LHSV of 3.0 h^?1. The catalytic performance of optimized 20Cu‐MCM‐41 catalyst could be attributed to the fine copper dispersion and large copper surface areas. © 2013 American Institute of Chemical Engineers AIChE J, 59: 2530–2539, 2013     

Simple but efficient synthesis of bis(indolyl)methanes by the condensation reaction of substituted benzaldehydes with indole over mesoporous ZrO<Subscript>2</Subscript>–MgO green catalysts under solvent free conditions

Solid base catalytic materials such as ZrO₂, MgO, ZrO₂–MgO were prepared by either precipitation or impregnation method and characterized by, BET, CO₂-TPD, PXRD, FT-IR, ICP-OES and TEM techniques. These catalysts were used for the synthesis of bis(indolyl)methanes by the condensation of different benzaldehydes with indole under solvent free conditions in shorter reaction times (20 min) at moderate temperature (70?°C). ZrO₂/MgO catalyst was found to be highly basic and also resulted in high yields of bis(indolyl)methanes up to ~99%. This methodology offers several advantages such as high quality yields, easy procedure, mild and environmentally benign conditions. TEM studies revealed that ZrO₂–MgO is mesoporous (25–45 nm) in nature. ZrO₂–MgO catalysts were found to be economical, efficient and were found to be highly active, recyclable and reusable up to six reaction cycles without much loss of their activity.     

Catalytic Hydrogenation for Bio‐Oil Upgrading by a Supported NiMoB Amorphous Alloy

A method of ultrasound‐assisted reduction of a nickel‐ammonia complex with borohydride in aqueous solution was used to prepare NiMoB/MCM‐41 and NiMoB/SBA‐15 supported amorphous alloy catalysts. These catalysts were used to upgrade bio‐oil at mild temperatures ranging from 100 to 160 °C and recycling of these two supported catalysts and of unsupported NiMoB was carried out. Then, fresh and third time used catalysts were characterized by X‐ray diffraction, X‐ray photoelectron spectra, and transmission electron microscopy. Quantitative results were obtained from the analysis of gas chromatography/mass spectrometry. Through mild upgrading, 1‐hydroxy‐2‐propanone, furfural, and 2‐methoxy‐4‐vinylphenol in the bio‐oil were converted to relevant alcohols and saturated phenols. The conversion rates were 45.7, 71.5, and 57.1 %, respectively, when crude bio‐oil was upgraded using NiMoB/MCM‐41 at 160 °C. The two supported catalysts, especially NiMoB/MCM‐41, had smaller amorphous NiMoB particles and exhibited more uniform dispersion on mesoporous silica, leading to higher reaction activity and stability than unsupported NiMoB. Deactivation of these catalysts resulted from the reduction of Ni⁰, B⁰, and Mo⁴⁺ species on the surface, the transition from the amorphous to the crystalline state, particle agglomeration, and coke deposition on the surface.     

Biodiesel production from waste cooking oil over alkaline modified zirconia catalyst

Screening and catalytic activity of alkaline modified zirconia i.e. Mg/ZrO₂, Ca/ZrO₂, Sr/ZrO₂, and Ba/ZrO₂ as heterogeneous catalyst in biodiesel production from waste cooking oil (WCO) have been investigated. The catalysts were prepared via wet impregnation of alkaline nitrate salts supported on zirconia. Physico-chemical characteristics of the catalysts were analyzed by BET surface area, XRD, FESEM and CO₂–NH₃–TPD. Among the catalysts screened, Sr/ZrO₂ exhibited higher catalytic activities. Characterization results disclosed Sr/ZrO₂ catalyst possessed balanced basic and acid site concentrations with its pore volume, surface area as well as pore diameters suitable for biodiesel production. The balanced active sites facilitated simultaneous transesterification and esterification of WCO. A plausible mechanism has been suggested for the simultaneous reactions. The effects of operating process conditions such as methanol to oil molar ratio, reaction temperature and catalyst loading on biodiesel production in the presence of Sr/ZrO₂ were investigated. Methyl ester (ME) yield at 79.7% was produced over 2.7 wt.% catalyst loading (Sr/ZrO₂), 29:1 methanol to oil molar ratio, 169 min of reaction time and 115.5 °C temperature.     

Novel inexpensive transition metal phosphide catalysts for upgrading of pyrolysis oil via hydrodeoxygenation

Supported molybdenum/molybdenum‐phosphides as inexpensive catalysts for bio‐oil hydrodeoxygenation (HDO) were in‐house prepared using different support materials, i.e., Al₂O₃, activated carbon (AC), MgAl₂O₄, and Mg₆Al₂(CO₃)(OH)₁₆. The HDO activity of these catalysts were investigated using a 100 mL bench‐scale reactor operating at 300°C with an initial hydrogen pressure of 50 bar for 3 h with a pyrolysis oil (PO). The catalytic efficiencies for bio‐oil HDO for the catalysts were compared with the expensive but commercially available Ru/C catalyst. Addition of small amount of P to the Mo catalysts supported on either AC and Al₂O₃ led to increased degree of deoxygenation (DOD) and oil yield compared with those without P. MoP supported on AC (MoP/AC) demonstrated bio‐oil HDO activity comparable to the Ru/C catalyst. Furthermore, three AC‐supported metal phosphides for PO HDO were compared under the same conditions, and they were found to follow the order of NiP/AC > CoP/AC > MoP/AC. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3664–3672, 2016     

Selective Hydrogenation of Cinnamaldehyde over Pt/ZrO2 Catalyst Modified by Cr, Mn, Fe, Co and Ni

Hydrogenation properties of cinnamaldehyde (CMA) have been studied over Pt/ZrO₂ and PtM/ZrO₂ catalysts (M = Cr, Mn, Fe, Co and Ni) in ethanol at 343 K and 2.0 MPa. The effect of different content of Ni and base has also been investigated over PtNi/ZrO₂ catalyst. With introduction of transition metals to Pt/ZrO₂ catalyst shows a significant influence on the catalytic properties. PtCo/ZrO₂ catalysts show the best yield of cinnamyl alcohol (CMO), and PtNi/ZrO₂ catalyst shows good yield of hydrocinnamaldehyde (HCMA). In the presence of base solution, rate of the hydrogenation of CMA over PtNi/ZrO₂(0.4 wt%) catalyst increases significantly and side reaction is remarkably inhibited. More bare metal atoms situated remote from the interface region on PtNi/ZrO₂ catalyst surface are the reason of good selectivity of HCMA for PtNi/ZrO₂ catalyst.     

催化剂与催化方式对生物质/塑料共热解的影响

首先使用HZSM⁃5作为催化剂，探究原位与异位催化方式对生物质与塑料共热解过程的影响。之后对HY、HZSM⁃5和Fe/HZSM⁃5 3种催化剂进行全面表征，进一步对比研究三者对生物质与塑料共热解过程的影响，并对3种催化剂积炭失活行为进行了分析。结果表明，原位催化生物油产率高于异位催化，但是异位催化方式强化了“双烯合成”和芳构化等反应，显著提升了芳烃的选择性，高达82.8 %。过渡金属Fe的引入提高了催化剂抑制积炭的能力，Fe/HZSM⁃5催化剂结焦量远少于HY和HZSM⁃5催化剂，仅为3.77 %。同HZSM⁃5相比， Fe/HZSM⁃5中Brönsted酸强度减弱，略微降低了碳氢化合物的选择性，但是将碳氢化合物中芳烃的选择性提高了16.7 %。由于焦炭的附着，反应后的催化剂比表面积、孔容和酸强度均有所降低，进而降低了其催化活性。     

Steam Reforming of Bio‐Oil for Hydrogen Production: Effect of Ni‐Co Bimetallic Catalysts

Various Ni‐Co bimetallic catalysts were prepared by incorporating sol‐gel and wet impregnation methods. A laboratory‐scale fixed‐bed reactor was employed to investigate their effects on hydrogen production from steam reforming of bio‐oil. The catalyst causes the condensation reaction of bio‐oil, which generates coke and inhibits the formation of gas at temperatures of 250 °C and 350 °C. At 450 °C and above the transformation of bio‐oil is initiated and gaseous products are generated. The catalyst also can promote the generation of H₂ as well as the transformation of CO and CH₄ and plays an active role in steam reforming of bio‐oil or gaseous products from bio‐oil pyrolysis. The developed 3Ni9Co/Ce‐Zr‐O catalyst achieved maximum hydrogen yield and lowest coke formation rate and provided a better stability than a commercial Ni‐based catalyst.     

SO42−/ZrO2 supported on γ‐Al2O3 as a catalyst for CO2 desorption from CO2‐loaded monoethanolamine solutions

In this work, the composite catalysts, SO₄²/ZrO₂/γ‐Al₂O₃ (SZA), with different ZrO₂ and γ‐Al₂O₃ mass ratios were prepared and used for the first time for the carbon dioxide (CO₂)‐loaded monoethanolamine (MEA) solvent regeneration process to reduce the heat duty. The regeneration characteristics with five catalysts (three SZA catalysts and two parent catalysts) of a 5 M MEA solution with an initial CO₂ loading of 0.5 mol CO₂/mol amine at 98°C were investigated in terms of CO₂ desorption performance and compared with those of a blank test. All the catalysts were characterized using X‐ray diffraction, Fourier transform infrared spectroscopy, N₂ adsorption–desorption experiment, ammonia temperature programmed desorption, and pyridine‐adsorption infrared spectroscopy. The results indicate that the SZA catalysts exhibited superior catalytic activity to the parent catalysts. A possible catalytic mechanism for the CO₂ desorption process over SZA catalyst was proposed. The results reveal that SZA1/1, which possesses the highest joint value of Brφnsted acid sites (BASs) and mesopore surface area (MSA), presented the highest catalytic performance, decreasing the heat duty by 36.9% as compared to the catalyst‐free run. The SZA1/1 catalyst shows the best catalytic performance as compared with the reported catalyst for this purpose. Moreover, the SZA catalyst has advantages of low cost, good cyclic stability, easy regeneration and has no effect on the CO₂ absorption performance of MEA. © 2018 American Institute of Chemical Engineers AIChE J, 64: 3988–4001, 2018     

Effect of oxygen capacity and oxygen mobility of supported Mg3(VO4)2 catalysts on the performance in the oxidative dehydrogenation of n-butane

Vanadium-magnesium oxide (Mg₃(VO₄)₂) catalysts supported on Al₂O₃, ZrO₂, MgO, and CeO₂ were prepared by a wet impregnation method, and they were applied to the oxidative dehydrogenation of n-butane. Effect of oxygen capacity and oxygen mobility of supported Mg₃(VO₄)₂ catalysts on the catalytic performance in the oxidative dehydrogenation of n-butane was investigated. Experimental results revealed that large oxygen capacity of the catalyst was favorable for obtaining high catalytic activity at the initial stage of reaction, while facile oxygen mobility of the catalyst led to stable catalytic activity during the catalytic reaction in the oxidative dehydrogenation of n-butane.     

Preparation of Zirconia Promoted Sulfated Titania System with High Catalytic Activity

SO₄^2–/TiO₂‐ZrO₂ (STZ) solid superacid catalysts were prepared using the coprecipitation‐impregnation method and characterized by FT‐IR, XRD, NH₃‐TPD, N₂ adsorption‐desorption isotherms, and SEM. It was observed that the sulfur content and the specific surface area of STZ changes with the ZrO₂ content, and passes through a maximum at Zr/Ti = 1/4. The results indicate that the molar ratio of Zr/Ti and nonionic surfactant, PEG, were helpful for increasing the surface areas and stabilizing the sulfate species on the surfaces of the catalysts. The catalytic activity results were supported by the hydrolysis reaction rate of 2‐methyl‐1,3‐dioxane (2MD) that was strongly dependent on the sulfur content in the zirconia promoted sulfated titania catalyst.     

The relationship between the structure and catalytic performance Cu/ZnO/ZrO2 catalysts for hydrogenation of dimethyl 1,4-cyclohexane dicarboxylate

The gas-phase hydrogenation of dimethyl 1,4-cyclohexane dicarboxylate to 1,4-cyclohexane dimethanol (CHDM) was conducted on well-dispersed supported Cu/ZnO/ZrO₂ catalysts. The results indicated that the structure and catalytic performance of resulting copper-based catalysts were profoundly affected by the addition of zirconium. Moreover, the as-synthesized catalyst with 35.0 wt.% ZrO₂ component was found to exhibit superior catalytic performance with a high CHDM yield of 96.8% to other catalysts, which should be mainly attributed to the significant dispersion effect of ZrO₂ on the copper-containing species resulting in a higher metallic copper surface area as well as a larger number of Cu⁺ species.     

Total Oxidation of Methane and Chlorinated Hydrocarbons on Zirconia Supported A1–xSrxMnO3 Catalysts

The catalytic behavior of ZrO₂ and ZrO₂ containing 8 mol‐% Y₂O₃ supported A_1–xSr_xMnO₃ (A = La, didymium) perovskites was studied in the total oxidation of methane, chloromethane and dichloromethane considering catalyst deactivation and byproduct formation. The perovskites are dispersed on the support surface; clusters with a perovskite‐like structure were formed. The supported catalysts are characterized by higher specific surface areas compared with the unsupported ones. Partial substitution of A‐site cations by Sr leads to an enhancement of the catalytic activity in the total oxidation of methane, but not in the total oxidation of chlorinated hydrocarbons (CHC). The catalytic activity of supported and unsupported catalysts is comparable in the total oxidation of methane in spite of the significantly lower perovskite content of the supported catalysts. In the CHC conversion the catalytic activity of the supported catalysts is higher than that of the unsupported ones.     

Cordierite Honeycomb Monoliths Coated with Zirconia and Its Modified Forms for Biodiesel Synthesis from Pongamia glabra

This study investigates the use of cordierite honeycomb monoliths coated with solid acids such as zirconia, Mo(VI)/ZrO₂ and Pt‐SO₄^2?/ZrO₂ and solid bases like zirconia–calcia, zirconia–magnesia mixed oxides in the synthesis of biodiesel from oil (PG‐oil). Solid acids were used for the esterification of free fatty acids in PG‐oil with methanol to reduce the percentage of free fatty acids in the oil followed by transesterification of PG‐oil over solid bases to synthesize biodiesel. The oxide catalysts were coated on honeycombs by an impregnation technique and characterized for their surface acidity/basicity, crystallinity and morphology. The effect of the molar ratio of PG‐oil/methanol in esterification and transesterification was studied. Reactivation and reusability of both solid acid and solid base catalysts was investigated. The catalysts were also prepared in their powder forms and their activity was compared with that of honeycomb coated forms. A twofold increase in the yield of biodiesel was obtained when the catalysts were used in honeycomb coated forms. The results revealed that the honeycombs coated with mixed oxides such as zirconia–calcia and zirconia–magnesia were economical, efficient and eco‐friendly (3e concept) for biodiesel production with ~95 % yield.     

Selective acetylation of glycerol over CeO2–M and SO42−/CeO2–M (M = ZrO2 and Al2O3) catalysts for synthesis of bioadditives

The feasibility of acetylation of glycerol with acetic acid was investigated employing CeO₂–ZrO₂, CeO₂–Al₂O₃, SO₄^2?/CeO₂–ZrO₂, and SO₄^2?/CeO₂–Al₂O₃ solid acid catalysts to synthesize monoacetin, diacetin and triacetin having interesting applications as bioadditives for petroleum fuels. Intensive physicochemical and surface characterization of the prepared catalysts were performed using XRD, BET surface area, ammonia-TPD and Raman spectroscopy techniques. Characterization results revealed that impregnated sulfate ions strongly influence the physicochemical characteristics of the investigated mixed oxide catalysts. Among various catalysts investigated, the SO₄^2?/CeO₂–ZrO₂ combination catalyst exhibited superior catalytic activity under mild conditions. The effect of various parameters such as reaction temperature, molar ratio of acetic acid to glycerol, catalyst wt% and time-on-stream were studied over the SO₄^2?/CeO₂–ZrO₂ catalyst to optimize the reaction conditions. Catalyst reusability was also carried out to understand its stability.