Catalyst Mixture Research Articles

Equilibrium catalyst from a fluidized catalytic cracking unit separated by metal content by using carbon nanotubes and a biphasic system

AbstractDuring fluid catalytic cracking (FCC) operations FCC catalyst particles become contaminated with various metals. These metals impact FCC performance and currently requires equilibrium catalyst (ECAT) mixtures consisting of a blend of FCC particles with a time spent in the reactor ranging from minutes to several months to be continuously extracted and sold as low value products or sent to landfills. Here a unique method to recycle FCC ECAT particles is presented, which separates ECAT particles by metal content by synthesizing carbon nanotubes and nanofibers on the ECAT particles surface and using a biphasic system. ECAT with low metal content can be sent back to the FCC unit for further use while ECAT with high metal content can be used for other purposes. Further, we show these treated ECAT materials of high metals content will absorb oil on the surface of water and may prove useful for oil spill clean‐up applications.

Realizing high conversion of syngas to gasoline-range liquid hydrocarbons on a dual-bed-mode catalyst

Achieving high conversion of syngas to fuels and basic chemicals with excellent selectivity and stability remains a challenge. Here, we report an 80.6% selectivity of gasoline-range C 5–11 hydrocarbons at 86.3% CO conversion over a dual-bed catalyst (CZA + Al 2 O 3 )/N-ZSM-5(97) that consists of an upper-bed syngas-to-dimethyl ether (DME) catalyst (CZA + Al 2 O 3 ) and a lower-bed DME-to-gasoline catalyst (nano-sized N-ZSM-5(97) zeolite). This dual-bed catalyst exhibits an excellent stability in a 110-h reaction test. The iso / n -paraffin ratio in the C 5–11 is up to 18. For the lower-bed zeolite catalyst, the nano-sized structure is beneficial to reduce coke and prolong lifetime; meanwhile, the low acid content is advantageous to increase C 5–11 selectivity. The 2,3-dihydro-1H-inden-1-one species can be definitely detected and identified in the spent lower-bed micro-sized M-ZSM-5(18) catalyst. They are regarded as intermediates to generate polycyclic aromatics, which generally lead to catalyst deactivation. The dual-bed catalyst (CZA + Al 2 O 3 )/N-ZSM-5(97) suggests a promising application in producing gasoline from syngas. • High and selective conversion of syngas to gasoline is achieved by a dual-bed catalyst • The dual-bed catalyst contains upper CZA + Al 2 O 3 and lower N-ZSM-5(97) catalysts • Nano-sized structure of N-ZSM-5(97) is beneficial to reduce coke and prolong lifetime • The low acid content of N-ZSM-5(97) helps to increase gasoline selectivity Because of the gradual depletion and non-renewability of petroleum, the use of non-petroleum resources instead of petroleum is of great significance. This alternative route can be generally achieved through syngas chemistry. The primary transportation fuel gasoline, which contains hydrocarbons with 5–11 carbons and is now almost derived from petroleum, can also be produced from non-petroleum syngas by some methods. However, stably obtaining high gasoline selectivity at high syngas conversion is still challenging. We have achieved this goal by designing a dual-bed catalyst (CZA + Al 2 O 3 )/N-ZSM-5(97) that includes a syngas-to-dimethyl ether (DME) catalyst CZA + Al 2 O 3 in the upper bed and a DME-to-gasoline catalyst N-ZSM-5(97) in the lower bed. This dual-bed catalyst suggests a promising application in producing gasoline from syngas. An 80.6% selectivity of gasoline-range hydrocarbons at 86.3% CO conversion can be achieved over a dual-bed catalyst that consists of a syngas-to-DME catalyst CZA + Al 2 O 3 (a mixture of CuZnAl methanol synthesis catalyst and acidic γ-Al 2 O 3 catalyst) in the upper bed and a DME-to-gasoline catalyst N-ZSM-5(97) (nano-sized H-ZSM-5 zeolite with Si/Al ratio = 97) in the lower bed. The dual-bed catalyst suggests a promising application in producing gasoline from syngas.

Transesterification of Waste Cooking Oil Using Bone and Eggshell Mixture as a Catalyst

Reuse of waste such as eggshells and animal bones as a catalyst to convert waste cooking oil into biodiesel fuel was investigated. A mixture of bone and eggshell waste (50:50) was used as a catalyst for biodiesel production from waste cooking oil. Different calcination temperatures have been investigated for the catalyst and the highest production of biodiesel was found at 900°C. The experimental results showed that a methanol/oil ratio of 15:1, a mixture of bone and eggshell catalyst (900°C, 2 h) of 12 wt.%, a reaction temperature of 60°C gave a biodiesel yield of 94% at 4 h. The effects of calcination temperature and catalyst leaching were examined. The catalysts were characterized by x-ray diffraction, N2 adsorption-desorption, x-ray photoelectron spectroscopy, and Fourier-transform infrared spectrometry.

Model Analysis of the Role of Kinetics, Adsorption Capacity, and Heat and Mass Transfer Effects in Sorption Enhanced Dimethyl Ether Synthesis.

The role of kinetics, adsorption capacity, and heat and mass transfer effects in the sorption enhanced dimethyl ether synthesis (SEDMES) is investigated by means of a 2D+1D model of a single tube of an industrial-scale, externally cooled, multitubular reactor that simulates the reaction/adsorption step of the SEDMES cycle. The effect of the adsorbent/catalyst weight ratio is analyzed, showing that a trade-off between DME productivity and yield originates from the balance of kinetics and adsorption capacity in the reactor tube. The effects of internal diffusion in catalyst particles are shown to have a strong impact on effective reaction rates: significant yield/productivity improvements are obtained when using a mechanical mixture of catalysts with small particle diameters or by rearranging the distribution of the two active phases in hybrid or core@shell pellets. The thermal effects in the reactor, which are increasingly critical upon intensifying the SEDMES process conditions, are also addressed.

Thermochemical Energy Storage Performance Analysis of (Fe,Co,Mn)Ox Mixed Metal Oxides

Metal oxide materials are known for their ability to store thermochemical energy through reversible redox reactions. Metal oxides provide a new category of materials with exceptional performance in terms of thermochemical energy storage, reaction stability and oxygen-exchange and uptake capabilities. However, these characteristics are predicated on the right combination of the metal oxide candidates. In this study, metal oxide materials consisting of pure oxides, like cobalt(II) oxide, manganese(II) oxide, and iron(II, III) oxide (Fe3O4), and mixed oxides, such as (100 wt.% CoO, 100 wt.% Fe3O4, 100 wt.% CoO, 25 wt.% MnO + 75 wt.% CoO, 75 wt.% MnO + 25 wt.% CoO) and 50 wt.% MnO + 50.wt.% CoO), which was subjected to a two-cycle redox reaction, was proposed. The various mixtures of metal oxide catalysts proposed were investigated through the thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), energy dispersive X-ray (EDS), and scanning electron microscopy (SEM) analyses. The effect of argon (Ar) and oxygen (O2) at different gas flow rates (20, 30, and 50 mL/min) and temperature at thermal charging step and thermal discharging step (30–1400 °C) during the redox reaction were investigated. It was revealed that on the overall, 50 wt.% MnO + 50 wt.% CoO oxide had the most stable thermal stability and oxygen exchange to uptake ratio (0.83 and 0.99 at first and second redox reaction cycles, respectively). In addition, 30 mL/min Ar–20 mL/min O2 gas flow rate further increased the proposed (Fe,Co,Mn)Ox mixed oxide catalyst’s cyclic stability and oxygen uptake ratio. SEM revealed that the proposed (Fe,Co,Mn)Ox material had a smooth surface and consisted of polygonal-shaped structures. Thus, the proposed metallic oxide material can effectively be utilized for high-density thermochemical energy storage purposes. This study is of relevance to the power engineering industry and academia.

MCM-41-supported tungstophosphoric acid as an acid function for dimethyl ether synthesis from CO2 hydrogenation

We mixed an MCM-41-supported tungstophosphoric acid (TPA) catalyst with a commercial CuO–ZnO–Al2O3 methanol synthesis catalyst (MSC) and optimized the mixing ratios/reaction conditions towards high performance in dimethyl ether (DME) synthesis by CO2 hydrogenation. First, a series of TPA/MCM-41 catalysts were synthesized at a TPA loading of 30, 40, 60, and 80 wt% and characterized by combining various techniques. The results of X-ray fluorescence spectroscopy confirmed the loading of stoichiometric TPA amounts in each TPA/MCM-41 catalyst, while the N2 adsorption-desorption measurements and the scanning transmission electron microscopy images were showing the decoration of MCM-41 pores with TPA clusters. X-ray diffraction and infrared spectroscopy results identified some structural distortions in TPA clusters especially at relatively low loadings and the results of temperature programmed desorption of ammonia measurements quantified the consequences of these changes in TPA structure on the acid properties. The optimized TPA loading in TPA/MCM-41 was 60 wt% with CuO–ZnO–Al2O3:TPA/MCM-41 = 4:1 at 40 000 mL CO2 gcat−1 h−1 and H2:CO2 = 3:1 at 250 °C and 45 bar. At these conditions, the rate was 1551.5 gDME kgcat−1 h−1, to the best of our knowledge, the highest rate for the direct DME synthesis from CO2 hydrogenation in a single-pass reactor. This performance was originated from the high density of acid sites in TPA/MCM-41 owing to exceptionally high surface area of MCM-41 offering a monolayer dispersion of TPA even at a TPA loading of 60 wt%. These results present a broad potential of TPA/MCM-41 as an acid function in the catalyst mixture for the single-pass DME synthesis from CO2 hydrogenation, especially if used together with an MSC specifically designed for CO2 hydrogenation.

Engineered biochars from catalytic microwave pyrolysis for reducing heavy metals phytotoxicity and increasing plant growth

Pb, Ni, and Co are among the most toxic heavy metals that pose direct risks to humans and biota. There are no published studies on biochars produced at low temperatures (i.e., 300 °C), which possess high sorption capacity for heavy metal remediation and reclamation of contaminated sandy soils. This research studied the effect of catalytic microwave pyrolysis of switchgrass (SG) using bentonite and K3PO4 to produce biochar at low temperature (300 °C) with high sorption capacity for reducing the phytotoxicity of heavy metals, and investigated the synergistic effects of catalyst mixture on biochar sorption capacity. The quality of the biochars was examined in terms of their impacts on plant growth, reducing phytotoxicity and uptake of heavy metals in sandy soil spiked with Pb, Ni, and Co. All catalysts increased the micropore surface area and cation-exchange capacity of biochars, and resulted in biochars rich in plant nutrients, which not only decreased heavy metal phytotoxicity, but also boosted plant growth in the spiked soil by up to 140% compared to the sample without biochar. By mixing bentonite and K3PO4 with SG during microwave pyrolysis, the efficacy of biochar in reducing phytotoxicity and heavy metals uptake was further enhanced because of the highest micropore surface area (402 m2/g), moderate contents of Ca, Mg, K, and Fe for ion-exchange and moderate concentration of phosphorus for the formation of insoluble heavy metal compounds. Generally, the biochar created at 300 °C (300-30KP) showed similar performance to the biochar created at 400 °C (400-30KP) in terms of reducing heavy metal bioavailability.

Nickel-Catalyzed N-Arylation of Amides with (Hetero)aryl Electrophiles by Using a DBU/NaTFA Dual-Base System

AbstractThe first nickel-catalyzed N-arylation of amides with (hetero)aryl (pseudo)halides employing an organic amine base is described. By using a bis(cyclooctadienyl)nickel/8-[2-(dicyclohexylphosphinyl)phenyl]-1,3,5,7-tetramethyl-2,4,6-trioxa-8-phosphaadamantane catalyst mixture in combination with DBU/NaTFA as a dual-base system, a diversity of (hetero)aryl chloride, bromide, tosylate, and mesylate electrophiles were successfully cross-coupled with structurally diverse primary amides, as well as a selection of secondary amide, lac­tam, and oxazolidone nucleophiles.

Comparative simulation study of methanol production by CO2 hydrogenation with 3A, 4A and 5A zeolites as adsorbents in a PSA reactor

In this work, the performance of 3A, 4A and 5A zeolites in a PSA reactor to obtain methanol by CO2 hydrogenation has been compared by numerical simulation. Henry's constants of adsorption and the reciprocal diffusion time constants of water and methanol in these adsorbents have been measured in the reaction temperature range (200–350 °C) to simulate their performance using a zeolite/Cu-ZnO-Al2O3 catalyst mixture. A new cycle has been proposed for PSA reactors including a complete recirculation of heavy product, without using a purge. The best performance is obtained with 3A zeolite, having the lower water and methanol affinities facilitating bed regeneration. With the proposed process, methanol can be produced from CO2 hydrogenation at 250 °C and 50 bar with a conversion of 99.6% in one step, a selectivity of 83–96%, and productivities of 0.023–0.13 mol m3 s−1. The process has minimal loss of H2 in the form of water (1 mol H2O/mole converted CO2).

K2CO3 in NH4OH as an Effective Catalyst Mixture for the Transesterification of High Acid Value Mahua Oil

In present study, biodiesel was synthesized from high free fatty acid content Mahua oil using K2CO3 in NH4OH catalyst mixture through transesterification process. Addition of NH4OH to K2CO3, enhanced the basic strength of the catalyst (K2CO3) by generating in-situ KOH in ammonium carbonate medium. The presence of ammonium carbonate in the reaction medium controlled the generation of intermediate water during methoxide formation and thereby increased the biodiesel yield. The maximum yield of 98.5% with a fatty acid methyl ester (FAME) content of 98.95% was obtained at the optimized condition of catalyst mixture of 1g K2CO3 in 0.5 g of NH4OH, oil to methanol molar ratio 1:7 at 55 ºC in 75 min. Characterization of the obtained biodiesel has been carried out using GC-MS and 1H NMR techniques. The physico-chemical properties of the oil and the synthesized biodiesel were tested according to the ASTM D6751 standards and the values are within the range.

Preparation of 1,2-substituted benzimidazoles via a copper-catalyzed three component coupling reaction.

1,2-Substituted benzimidazoles were prepared by simply stirring a mixture of copper catalysts, N-substituted o-phenylenediamines, sulfonyl azides and terminal alkynes. Particularly, the intermediate N-sulfonylketenimine occurred with two nucleophilic addition and the sulfonyl group was eliminated via cyclization. In a way, sulfonyl azides and copper catalysts activated the terminal alkynes to synthesize benzimidazoles.

A Self-Jet Vapor-Phase Growth of 3D FeNi@NCNT Clusters as Efficient Oxygen Electrocatalysts for Zinc-Air Batteries.

Development of highly active, robust electrocatalysts to accelerate the sluggish oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is crucial and challenging for the practical application of metal-air batteries. In this effort, a novel and facile self-jet vapor-phase growth approach is developed, from which highly dispersive FeNi alloy nanoparticles (NPs) encapsulated in N-doped carbon nanotubes (NCNT) grown on a cotton pad (FeNi@NCNT-CP) can be fabricated. The as-prepared FeNi@NCNT-CP clusters exhibit superior bifunctional catalytic activity, with a high half-wave potential of 0.85V toward ORR and a low potential of 1.59V at 10mA cm-2 toward OER. Specifically, owing to the synergistic effects of FeNi alloy NPs and NCNT, FeNi@NCNT-CP clusters deliver excellent stability, demonstrating a small potential gap of 0.73V between ORR and OER after operation for 10000 cycles. Furthermore, FeNi@NCNT-CP serves as a cost-effective, superior catalyst for the cathode of a rechargeable Zn-air battery, outperforming a catalyst mixture of expensive Pt/C and IrO2 . FeNi@NCNT-CP provides a maximum power density of 200mW cm-2 and a cycling stability of up to 250 h. This contribution provides new prospects to prepare non-noble electrocatalysts for metal-air battery cathodes.

Produksi Biodiesel dari Dedak Padi dengan Metode In-Situ Dua Tahap Menggunakan Katalis Asam Sulfat dan CaO/Hydrotalcite

In this study, biodiesel is made from rice bran vegetable oil. Biodiesel production was carried out by the in-situ method using two-sides using sulfuric acid catalysts and CaO/hydrotalcite. The solvent used was methanol as an oil component in the material and a reactant in the formation of FAME and n-hexane as a solvent to increase the yield of rice bran oil extraction. CaO/hydrotalcite to the yield of biodiesel produced and composition of biodiesel at the highest yield. As much as 50 grams of rice bran was put into a three-neck flask, then 50 ml of n-hexane were added. Next, 1 ml mixture of a sulfuric acid catalyst and 250 ml of methanol were added. Then, the mixture was reacted at 65º. Add stirring to 600 rpm for 90 minutes. Reheating after 90 minutes and a sample of 2.5 grams was taken for FFA testing. Next, the CaO/hydrotalcite catalyst in 10 ml of methanol with a mass variation of 1; 1,5; and 2 grams are added to the reaction flask. The mixture was reacted again at a temperature of 65 ºSuitably stirrings 600 rpm for 90 minutes. Based on the BET test results, the CaO/hydrotalcite catalyst surface area was 200.13 m2/g. The best results obtained on CaO/hydrotalcite catalysts were 2 grams with a biodiesel yield of 9.56%. In the highest biodiesel yield, the FAME component is preferred over the oleic acid methyl ester composition with an area of 35.09% at a retention time of 19.14 min.

Synergistic Effects of Catalyst Mixtures on Biomass Catalytic Pyrolysis.

This paper studied the synergistic effects of catalyst mixtures on biomass catalytic pyrolysis in comparison with the single catalyst in a microwave reactor and a TGA. In general, positive synergistic effects were identified based on increased mass loss rate, reduced activation energy, and improved bio-oil quality compared to the case with a single catalyst at higher catalyst loads. 10KP/10Bento (a mixture of 10% K3PO4 and 10% bentonite) increased the mass loss rate by 85 and 45% at heating rates of 100 and 25°C/min, respectively, compared to switchgrass without catalyst. The activation energy for 10KP/10Bento and 10KP/10Clino (a mixture of 10% K3PO4 and 10% clinoptilolite) was slightly lower or similar to other catalysts at 30 wt.% load. The reduction in the activation energy by the catalyst mixture was higher at 100°C/min than 25°C/min due to the improved catalytic activity at higher heating rates. Synergistic effects are also reflected in the improved properties of bio-oil, as acids, aldehydes, and anhydrosugars were significantly decreased, whereas phenol and aromatic compounds were substantially increased. 30KP (30% K3PO4) and 10KP/10Bento increased the content of alkylated phenols by 341 and 207%, respectively, in comparison with switchgrass without catalyst. Finally, the use of catalyst mixtures improved the catalytic performance markedly, which shows the potential to reduce the production cost of bio-oil and biochar from microwave catalytic pyrolysis.

Thermal reaction characteristics of paraffin in the presence of combustion catalysts

Paraffin fuels are regarded to be the best solid fuel of hybrid rocket motor due to the high regression rate, low cost, and environment friendly products. However, the regression rate of the fuels still cannot completely meet the requirement of the motor. Catocene, copper chromite, and cobalt stearate have been used as the combustion catalysts in this study, where the simultaneous TG-FTIR-MS and TG experiments at different heating rates were carried to investigate the thermal behavior of paraffin and paraffin/combustion catalysts mixtures. The results showed that both paraffin and the mixtures could decompose or be oxidized into gases products almost completely, with the main decomposition product of C2H6 and oxidation products of C2H4O, CO, CO2, and H2O. There was only one stage for both decomposition and oxidation of paraffin, and the kinetic model of decomposition process are close to two-dimensional diffusion (D2 model); cobalt stearate favored the decomposition of paraffin owing to the higher pre-exponential factor and the lower activation energy, whereas only copper chromite played an obvious positive role in both oxidation and regression rate of paraffin.

Catalyzed Steam Gasification of Cistus Ladanifer Biochar

Gasification processes require the use of cheap and sustainable raw materials, as well as the optimization of the process, for a suitable commercial use. Cistus Ladanifer (rockrose) could be a suitable raw material for this purpose, as it grows spontaneously in Mediterranean regions, and might contribute to the economic development of these areas. In this research, a study about catalyzed gasification of Cistus Ladanifer biochar was carried out. The aim was to characterize the gaseous phase and to carry out a kinetic study. The experiments were carried out in a thermobalance connected to a gas chromatograph to quantify the exhaust gas. The operating variables studied were the initial carbon mass, temperature, steam partial pressure, the kind of catalyst (ionic or cationic), catalyst concentration and the method to incorporate the catalyst (impregnation or mixture). As a result, impregnation was the most effective way to mix the raw material and the catalyst, with K+ and CO32− as the most active cations and anions used in this experience, respectively. Temperature and steam partial vapor showed a positive effect on conversion and gas yield. The use of ideal models for gas-solid reactions showed acceptable results for the kinetic study.

DESIGN AND MANUFACTURE CHASSIS AND BODY OF SIMPLE GOKART USING AUTOMATIC CLUTCH AND 7.5 HP ENGINE POWER

Go-kart is a variant of a simple and small open-roof four-wheeled vehicle for motor sports. Go-kart usually races on small scale circuits. Go-kart racing is usually considered a stepping stone for motor sports that are higher and more expensive. The design of the karts is carried out by mechanical engineering students of the University of Riau based on the size of karts in general. The chassis is made of pipe with ASTM A53 pipe specifications with a tensile strength of 240 MPa with a dimension of length of 6.22 meters, an outer diameter of 33.40 mm and an inner diameter of 30.02 mm. Body building is done with fiber with a catalyst mixture ratio of 1:45. The process of painting with a ratio of primers and hardeners is 1: 4, and clear and hardener 4: 1. A kart with a chassis mass of 7.09 kg and a passenger of 70 kg has been produced, with dimensions of length 1100 mm, width of 610 mm, and distance between axes of 1050 mm. This karting uses the 1994 Astra grand engine with 7.5 HP of power, 6000 rpm rotation and 20 kg mass. The transmission system used is a double automatic type.

Continuous Sweat Lactate Sensor Based on Screen-Printed MgO-Templated Carbon with Integrated Flow System

Lactate has long been known as the indicator for distinguishing aerobic and anaerobic metabolism, and thus is a useful marker for metabolic disorders and the state of exercise [1]. Especially, the continuous monitoring of sweat lactate is a useful non-invasive method for real-time tracking the progress of exercise, e.g. of athletes, or of physical therapy patients. In biosensors for continuous monitoring, the biological recognition element, e.g. lactate oxidase (LOx) has to be immobilized on the electrode. Our group previously reported of a glucose sensor in which glucose dehydrogenase (GDH) was immobilized covalently on screen-printed MgO-templated mesoporous carbon (MgOC) modified by graft polymerization, and showed improved stability [2]. Likewise, in this study, radicals were introduced on the surface of the MgOC by electron beam irradiation. Next, glycidyl methacrylate (GMA) was polymerized on the radicalized MgOC, which resulted in epoxy groups on the surface. Ink was prepared by dispersing this poly(GMA)-MgOC (GMgOC) and a polyvinylidene difluoride (PVdF) derivative in N-methyl-2-pyrrolidone (NMP). The ink then was used for the final layer of the working electrode (WE) of a screen-printed 3-electrode strip. Next, 1,2-naphthoquinone was deposited on the WE as mediator, which is insoluble in water and thus is unlikely to dissolve into sweat during the measurement. Finally, LOx derived from Enterococcus faecium was immobilized on the WE by binding covalently to the epoxy groups. This combination of LOx immobilized on screen-printed GMgOC and naphthoquinone promises the construction of stable lactate biosensors suitable for continuous measurements.Furthermore, in this study, two other points were considered for the design and construction of the sensor device. Firstly, the sensor should be constantly supplied with a minimum amount of sweat, without the supply being interrupted. Secondly, the materials and texture of the parts of the sensor in direct contact with the skin should not be irritating. An integrated flow system can solve both points; it ensures a constant supply of sweat, and limits the material and texture in direct contact with the skin. For the construction of the flow system, first, a mold was formed on a silicon wafer using an epoxy-based negative photoresist. Next a degassed mixture of polydimethylsiloxane (PDMS) monomer and catalyst was poured over the mold and cured at 80°C for 1 hour.In first trials, the sensor and flow system were pressed together tightly onto artificial sweat glands. Leakage was prevented by constructing a connector for the sensor out of conducting adhesive tape. Potassium phosphate buffer (100 mM, pH 7.0) containing various amounts of sodium lactate were pumped through the system at 80 µL/min using a syringe pump. Figure 1a shows the response of this system to varying concentrations of lactate. The spikes at the change of concentration are due to a change in the flow when switching the syringe. The delay between the switch of the syringe and the change in response current is due to the lag time until the lactate reached the sensor. The plot of the response current vs the lactate concentration (Fig. 1b) shows a concentration dependent response up to 20 mM lactate. These results indicate that this system is suitable for measuring sweat lactate continuously. Acknowledgement: This work was partially supported by JST-ASTEP Grant Number JPMJTS1513, JSPS Grant Number 17H02162 and Private University Research Branding Project (2017-2019) from Ministry of Education, Culture, Sports, Science and Technology, and Tokyo University of Science Grant for President's Research Promotion． References [1] M.E. Payne, et al.; Sci. Rep., 9, 13720 (2019).[2] I. Shitanda, et al.; Bull. Chem. Soc. Jpn., 93, 32-36 (2020). Figure 1

Catalytic Pyrolysis of Lignocellulosic Biomass: The Influence of the Catalyst Regeneration Sequence on the Composition of Upgraded Pyrolysis Oils over a H-ZSM-5/Al-MCM-41 Catalyst Mixture.

Catalyst regeneration is economically attractive, and it saves resources. Thus, it is important to determine the influence of catalyst regeneration on the chemical composition of upgraded oil. The catalyst was regenerated several times, and the regenerated catalyst was reloaded in the reactor to proceed with the next run. The composition of the derived upgraded pyrolysis oils in relation to catalyst regeneration was determined. The results revealed that the catalyst cracking abilities decreased with an increased number of reaction cycles. The opposite trends of the organic fraction and water yields indicated that the deoxygenation process occurred via H2O production. A decrease in the CO and CO2 yields revealed that the deoxygenation in catalytic pyrolysis with a catalyst mixture occurred via decarbonylation, decarboxylation, and dehydration mechanisms. The chemical formula of bio-oil changed from CH0.17O0.91 for a noncatalytic experiment to CH0.14O0.66 for a catalytic pyrolysis experiment after five reaction cycles, which indicated that the oxygen in the bio-oil decreased at the expense of hydrogen. The high heating value (HHV) of bio-oils decreased as the number of reaction cycles increased, albeit the minimum value of 22.41 wt % in the 6th reaction cycle was still higher than the value for the noncatalytic experiment. Compared to the HHVs of diesel fuel and gasoline petrol, the values of the produced bio-oil with catalyst mixtures were still low. The catalyst regained 94% of the surface area for the fresh catalyst, which indicated that the regeneration procedure was effective.

Study of catalyst bed composition for the direct synthesis of dimethyl ether from CO2-rich syngas

In this work, we study the direct synthesis of DME using CO2-rich syngas, with a CO2/CO ratio similar to that obtained from the gasification of biomass, i.e., 1.9. We used catalytic beds consisting of physical mixtures of the benchmark catalysts used for the synthesis of methanol from syngas and for methanol dehydration to DME, namely Cu/ZnO/Al2O3 and γ-Al2O3, respectively. Our results show that the ratio between each catalytic phase determines the productivity and selectivity to DME, as well CO and CO2 conversions. Thus, higher total carbon conversions were obtained with the catalytic bed with the highest content of the Cu/Zn/Al2O3 phase. The presence of γ-Al2O3 allows to exceed the equilibrium conversion of CO for the syngas to methanol synthesis. The highest DME productivity is obtained with the catalytic bed containing equal amounts of both catalytic phases. In addition, we also show that other reaction variables such as temperature, pressure, and contact time also play an important role in terms of DME productivity. The presence of a high fraction of CO2 in the syngas results in a high production of H2O, which after long times on stream result in the deactivation of the Cu/ZnO/Al2O3 catalytic phase due to the sintering of the copper particles. The in situ removal of H2O via the addition of an H2O sorbent, zeolite 3A, into the catalytic bed, results in a significant enhancement of both carbon conversion and DME productivity.