Synthesis and Modification of SAPO-34 Nanoparticles by Incorporation of Metal Ions Using Rapid High Temperature Method

Considering studies done on the result of methanol conversion over SAP-34 molecular sieve, it is understood that increase of selectivity is ascribed to the increase of acidity in acid sites which is a result of incorporation of metal in crystal structure and decrease of crystal size. In this study, metal incorporation in the SAPO-34 structure leaded to increase of acid sites concentration but did not affect the acid strength distribution. The catalytic performance of the SAPO-34 nanoparticles in the MTO reaction varied according to their crystallite size. Decreasing particle size results in larger increase of external surface area and shorter diffusion path, both cause reduction in mass and heat transfer resistances in catalysis and sorption. In this work a rapid high-temperature synthesis method was developed to synthesis uniform nanoparticles of SAPO 34 zeolite with high crystallinity and metal was successfully incorporated in crystal structure. In order to investigate the effects of temperature and synthesis time on purity and crystallinity of the synthesized samples, the crystallization temperature was increased from 350 to 550 K while the synthesis time was decreased from 24 h to 45 min. The samples were characterized by XRD, BET and SEM analysis techniques. It was found that by using high temperature and short synthesis time the particle size decreased and the metal was properly incorporated into the crystal structure.

Download Full-text

Positive Role of Synthesis Method and Hard Template on the Catalytic Performance of SAPO-34 in Methanol to Olefin Reaction.

Combinatorial Chemistry & High Throughput Screening ◽

10.2174/1386207323666200720103321 ◽

2020 ◽

Vol 23 ◽

Author(s):

Sajjad Rimaz ◽

Reza Katal

Keyword(s):

Particle Size ◽

Synthesis Method ◽

Catalytic Performance ◽

Hard Template ◽

Structure Directing Agent ◽

Positive Role ◽

Methanol To Olefin ◽

Dg Method ◽

Synthesis Procedure

: In the present study, SAPO-34 particles were synthesized using hydrothermal (HT) and dry gel (DG) conversion methods in the presence of diethyl amine (DEA) as an organic structure directing agent (SDA). Carbon nanotubes (CNT) were used as hard template in the synthesis procedure to introduce transport pores into the structures of the synthesized samples. The synthesized samples were characterized with different methods to reveal effects of synthesis method and using hard template on their structure and catalytic performance in methanol to olefin reaction (MTO). DG conversion method results in smaller particle size in comparison with hydrothermal method, resulting in enhancing catalytic performance. On the other side, using CNT in the synthesis procedure with DG method results in more reduction in particle size and formation of hierarchical structure which drastically improves catalytic performance.

Download Full-text

CuZnZr-Zeolite Hybrid Grains for DME Synthesis: New Evidence on the Role of Metal-Acidic Features on the Methanol Conversion Step

Catalysts ◽

10.3390/catal10060671 ◽

2020 ◽

Vol 10 (6) ◽

pp. 671

Author(s):

Massimo Migliori ◽

Antonio Condello ◽

Francesco Dalena ◽

Enrico Catizzone ◽

Girolamo Giordano

Keyword(s):

Acid Catalyst ◽

Methanol Conversion ◽

Catalytic Performance ◽

Acid Sites ◽

Zeolite Catalysts ◽

Hybrid Catalyst ◽

Zeolite Structure ◽

Precipitation Medium ◽

Co Precipitation ◽

New Evidence

The assessment of the catalytic performance of “hybrid” metal/zeolite catalysts (based on FER or MFI structure and CuZnZr metal complexes) in the methanol dehydration step to DME has been studied in this work. The results clearly show that there is an important effect of the interaction between metal and acid sites affecting the acid catalyst performances. Additionally, deactivation, studied by means of a Timo-on-Stream (TOS) test, was affected by the type of zeolite structure used for hybrid catalyst preparation. The decrease in DME selectivity can be attributed to the cooperation of metal and acid sites in the production of different compounds (mainly methyl formate and dimethoxy methane) converting methanol and DME. The presence of these compounds (indicating different reaction pathways active) was found to be dependent on the zeolite structure and on the type of co-precipitation medium (water or ethanol) used to prepare the hybrid catalyst.

Download Full-text

Preparation of La1-xSrxMnO3 Materials by High Temperature Solid Phase Method

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.562-564.482 ◽

2012 ◽

Vol 562-564 ◽

pp. 482-485

Author(s):

Zeng Gang Li ◽

Zeng Yong Chu ◽

Yong Jiang Zhou ◽

Hai Feng Cheng

Keyword(s):

Crystal Structure ◽

Particle Size ◽

High Temperature ◽

Solid Phase ◽

Average Particle Size ◽

Phase Method ◽

Average Particle ◽

Structure And Morphology ◽

Solid Phase Method ◽

Perovskite Type

La1-xSrxMnO3 (LSMO) (x=0.1, 0.2, 0.3, 0.4)powders were synthesized by high temperature solid phase method, and the crystal structure and morphology were characterized by XRD and SEM. Results indicated that the pure perovskite type LSMO could be obtained after sintered at the temperature of 1000°C for 6h. The average particle size of the powders decreases with the increasing concentration of Strontium.

Download Full-text

The guiding role of pre-coking on the coke deposition over ZSM-5 in methanol to propylene

Royal Society Open Science ◽

10.1098/rsos.190218 ◽

2019 ◽

Vol 6 (9) ◽

pp. 190218 ◽

Cited By ~ 1

Author(s):

Lin Wang ◽

Jing Qi ◽

Hongqiao Jiao ◽

Liangcheng An ◽

Chong Guan ◽

...

Keyword(s):

High Temperature ◽

Thermogravimetric Analysis ◽

Methanol Conversion ◽

Acid Sites ◽

Coke Deposition ◽

Steam Treatment ◽

Elementary Analysis ◽

Before And After ◽

Propylene Selectivity

Deposition of carbonaceous compounds was used to improve the propylene selectivity of ZSM-5 by deactivating some acid sites meanwhile maintaining the high activity for methanol conversion. The carbonaceous species of pre-coked samples before and after MTP reactions were investigated by elementary analysis and thermogravimetric analysis (TGA). The results showed that pre-coke formed at low temperature (250°C) was unstable and easy to transform into polyaromatics species at the high reacting temperature, while combining 5% pre-coking process with 95% steam treatment at high temperature (480°C) was effective in inhibiting the formation of coke deposits and presented a significant improvement in the propylene selectivity.

Download Full-text

Synthesis of Ni-Modified ZSM-5 Zeolites and Their Catalytic Performance in n-Octane Hydroconversion

Frontiers in Chemistry ◽

10.3389/fchem.2020.586445 ◽

2020 ◽

Vol 8 ◽

Author(s):

Qiang Wei ◽

Pengfei Zhang ◽

Xiaodong Liu ◽

Wenbin Huang ◽

Xiayun Fan ◽

...

Keyword(s):

Supported Catalysts ◽

Synthesis Method ◽

Textural Properties ◽

Catalytic Performance ◽

Acid Sites ◽

Impregnation Method ◽

Isomerization Selectivity ◽

Nimo Catalysts ◽

Adsorption Desorption

Ni-modified ZSM-5 zeolites with different nickel contents were successfully prepared by the in situ synthesis method and the impregnation method. The synthesized samples were characterized by XRD, SEM, N2 adsorption–desorption isothermals, and Py-FTIR. The characterization results show that both the textural properties and crystallization of Ni-modified ZSM-5 zeolites were preserved well, and their acidic properties can be modulated after nickel modification. The corresponding NiMo catalysts supported on Ni-modified ZSM-5 zeolites were prepared by the incipient wetness co-impregnation method, and their catalytic performances were evaluated in n-octane hydroconversion. Compared to the those modified by the in situ synthesis method, ZSM-5 zeolite-supported catalysts modified by the impregnation method exhibit higher stability and higher isomerization selectivity. This is due to the synergistic effect between Brønsted acid sites and Lewis acid sites on the Ni-modified ZSM-5 zeolites, especially for the NiMo/1Ni-Z5 catalyst.

Download Full-text

Preparation and Catalytic Performance of Metal-Rich Pd Phosphides for the Solvent-Free Selective Hydrogenation of Chloronitrobenzene

Catalysts ◽

10.3390/catal9020177 ◽

2019 ◽

Vol 9 (2) ◽

pp. 177

Author(s):

Chunshan Lu ◽

Qianwen Zhu ◽

Xuejie Zhang ◽

Qiangqiang Liu ◽

Juanjuan Nie ◽

...

Keyword(s):

Crystal Structure ◽

Activated Carbon ◽

Selective Hydrogenation ◽

Synthesis Method ◽

Catalytic Performance ◽

Solvent Free ◽

Active Hydrogen ◽

Hydrogen Atoms ◽

Facile Synthesis ◽

Palladium Phosphide

A facile synthesis method of palladium phosphide supported on the activated carbon was developed. The effects of Pd precursors for phosphatization, phosphatization temperature, and the ratio of hypophosphite/Pd on the generation of palladium phosphide were investigated, and a generation mechanism of the Pd3P crystal structure is proposed. The results demonstrate that only PdO, rather than Pd or PdCl2, can transform into Pd phosphide without damage to the activated carbon. The penetration of P into the Pd particle can dramatically improve the dispersion of Pd species particles on the activated carbon. The generation of Pd phosphide greatly depends on the phosphatization temperature and the ratio of hypophosphite/Pd. An intact Pd3P crystal structure was obtained when the ratio of hypophosphite/Pd reached 32 and the phosphatization temperature was above 400 °C. The Pd3P supported on the activated carbon exhibited superior catalytic performance in terms of the hydrogenation of halonitrobenzenes to haloanilines because it had few L acids and B acids sites and could not generate deficient-electron active hydrogen atoms as electrophiles.

Download Full-text

Catalytic Longevity of Hierarchical SAPO-34/AlMCM-41 Nanocomposite Molecular Sieve In Methanol-to-Olefins Process

Combinatorial Chemistry & High Throughput Screening ◽

10.2174/1386207323666200428092404 ◽

2020 ◽

Vol 23 ◽

Author(s):

Hossein Roohollahi ◽

Rouein Halladj ◽

Sima Askari

Keyword(s):

Molecular Sieve ◽

Molecular Diffusion ◽

Methanol Conversion ◽

Catalytic Performance ◽

Acid Sites ◽

The Other ◽

Light Olefins ◽

Initial Reaction ◽

Pore Blockage ◽

Prepared Composite

: SAPO-34/AlMCM-41, as a hierarchical nanocomposite molecular sieve was prepared by sequential hydrothermal and dry-gel methods studied for catalytic conversion of methanol to light olefins. Pure AlMCM-41, SAPO-34, and their physical mixture were also produced and catalytically compared. Physicochemical properties of materials were mainly investigated using XRD, N2 isothermal adsorptiondesorption, FESEM, FT-IR, NH3-TPD, and TG/DTG/DTA techniques. Micro-meso hierarchy of prepared composite could be demonstrated by XRD and BET analyses. Catalytic performance of materials illustrated that the methanol conversion on the prepared composite was about 98% for 120 min which showed a higher activity than the other catalysts. The initial reaction selectivity to light olefins for the composite was also comparable with those for the other catalysts. Furthermore, the results revealed that SAPO-34/AlMCM-41 preparation decreased the concentration and strength of active acid sites of the catalyst which could beneficially affect the deposition of heavy molecular products on the catalyst. However, as observed, the prepared composite was deactivated in olefins production faster than pure SAPO-34. The small mean pore diameter of composite could be mainly responsible for its pore blockage and higher deactivation rate. Meanwhile, since the SAPO-34 prepared by dry-gel method had inherently high mesoporosity, the AlMCM-41 introduction didn't promote the molecular diffusion in the composite structure. The coke content was found 15.5% for deactivated composite smaller than that for the SAPO-34 catalyst which could be due to the pore blockage and deactivation of the composite in a shorter period.

Download Full-text

Facile and Rapid Synthesis of Durable SSZ-13 Catalyst using Choline Chloride Template for Methanol-to-Olefins Reaction

Catalysts ◽

10.3390/catal11101250 ◽

2021 ◽

Vol 11 (10) ◽

pp. 1250

Author(s):

Xiongchao Lin ◽

Sasha Yang ◽

Xiaojia Li ◽

Caihong Wang ◽

Yonggang Wang

Keyword(s):

Choline Chloride ◽

Strong Acid ◽

Methanol Conversion ◽

Catalytic Performance ◽

Acid Sites ◽

Weak Acid ◽

Rapid Synthesis ◽

Light Olefin ◽

Mto Reaction ◽

Strong Acid Sites

In the current study, a facile and rapid synthesis approach for a SSZ-13 catalyst using choline chloride (CC) as a template was proposed, and the catalytic performance for the methanol-to-olefins (MTO) reaction was examined. With a proper amount of CC addition (i.e., m(CC)/m(SiO2)=0.14), uniform and homogeneously distributed cubic SSZ-13 crystals were obtained within 4 h with lower aggregation. The synthesized catalyst demonstrated excellent porous features with a total specific surface area and mesopore volume of 641.71 m2·g−1 and 0.04 cm3·g−1, respectively. The optimized strong and weak acid sites on SSZ-13 were obtained by regulating the m(CC)/m(SiO2) ratio. The less strong acid sites and a larger amount of weak acid sites in the synthesized catalyst were conducive to the catalytic performance of the MTO reaction under a lower reaction temperature (450 °C). The appropriate acidity and well-developed pore structure of synthesized SSZ-13 could also slow down the carbon deposition rate and, thus, significantly improve the catalytic lifetime of the catalyst. The methanol conversion rate and initial selectivity of light olefin using the synthesized catalyst could maintain over 95% and 50%, respectively, and a lifetime of 172 min was achieved. Although the low olefin selectivity of the synthesized SSZ-13 catalyst was slightly lower than that of the purchased one, its desirable features were thought to have good potential for industrial application.

Download Full-text

Thermoelectric properties of Ni0.15Co3.85Sb12 and Fe0.2Ni0.15Co3.65Sb12 skutterudites prepared by HPHT method

Materials Science-Poland ◽

10.1515/msp-2017-0069 ◽

2017 ◽

Vol 35 (3) ◽

pp. 496-500 ◽

Cited By ~ 2

Author(s):

Lingjiao Kong ◽

Hongan Ma ◽

Yuewen Zhang ◽

Xin Guo ◽

Bing Sun ◽

...

Keyword(s):

Crystal Structure ◽

Thermal Conductivity ◽

High Pressure ◽

High Temperature ◽

Transport Properties ◽

Thermoelectric Properties ◽

Figure Of Merit ◽

Thermoelectric Figure Of Merit ◽

Thermoelectric Figure ◽

Synthesis Time

AbstractN-type polycrystalline skutterudite compounds Ni0.15Co3.85Sb12 and Fe0.2Ni0.15Co3.65Sb12 with the bcc crystal structure were synthesized by high pressure and high temperature (HPHT) method. The synthesis time was sharply reduced to approximately half an hour. Typical microstructures connected with lattice deformations and dislocations were incorporated in the samples of Ni0.15Co3.85Sb12 and Fe0.2Ni0.15Co3.65Sb12 after HPHT. Electrical and thermal transport properties were meticulously researched in the temperature range of 300 K to 700 K. The Fe0.2Ni0.15Co3.65Sb12 sample shows a lower thermal conductivity than that of Ni0.15Co3.85Sb12. The dimensionless thermoelectric figure-of-merit (zT) reaches the maximal values of 0.52 and 0.35 at 600 K and 700 K respectively, for Ni0.15Co3.85Sb12 and Fe0.2Ni0.15Co3.65Sb12 samples synthesized at 1 GPa.

Download Full-text