Immobilization of α-amylase onto K-10 montmorillonite: characterization and comparison of activity in a batch and a fixed-bed reactor

Abstractα-amylase was immobilized on acid-activated montmorillonite K-10 via adsorption and covalent linkage. The immobilized enzymes were characterized by X-ray diffraction (XRD), surface area measurements, 27Al nuclear magnetic resonance (NMR) and scanning electron microscopy (SEM). Surface area measurements indicate pore blockage due to linking of the enzyme in the vicinity of the pore mouth. The XRD demonstrates intercalation of enzyme upon immobilization. The NMR studies indicate that, during adsorption, tetrahedral Al sites are involved, while covalent binding occurs exclusively on the octahedral Al sites. The SEM images depict the changed morphology of the clay surface due to immobilization. The efficiency of immobilized enzymes for starch hydrolysis was tested in a batch and a fixed-bed reactor and the performances were compared. The immobilized α-amylase showed a broad pH profile and improved stability characteristics in both reactor types when compared to the free enzyme. The effectiveness factor increased in the fixed-bed reactor, implying that diffusional restrictions to mass transfer operate in the heterogeneous reaction and the use of a fixed-bed reactor leads to a reduction in these diffusional resistances. In the continuous run, 100% initial activity was maintained for 72 h, and after 96 h, >80% activity was retained.

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MgO Dispersed on Activated Carbon as Water Tolerant Catalyst for the Conversion of Ethanol into Butanol

Applied Sciences ◽

10.3390/app9071371 ◽

2019 ◽

Vol 9 (7) ◽

pp. 1371 ◽

Cited By ~ 1

Author(s):

Stefano Cimino ◽

Jessica Apuzzo ◽

Luciana Lisi

Keyword(s):

Activated Carbon ◽

Surface Area ◽

Fixed Bed ◽

High Water ◽

Fixed Bed Reactor ◽

High Dispersion ◽

Water Tolerance ◽

Butanol Yield

MgO supported on activated carbon (AC) with a load ranging from 10% to 30% has been investigated as catalyst for the conversion of ethanol into butanol at 400 °C in a fixed bed reactor at different GHSV. Catalysts have been characterized by XRD, SEM/EDX, and N2 physisorption at 77 K. The high dispersion of MgO into the pores of the support provides strongly enhanced performance with respect to bulk MgO. MgO/AC catalysts have been also tested under wet feed conditions showing high water tolerance and significantly larger butanol yield with respect to an alumina supported Ru/MgO catalyst. After wet operation, the increased surface area of the catalyst leads to better performance once dry feed conditions are restored.

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Experimental and Computational Demonstration of a Low-Temperature Waste to By-Product Conversion of U.S. Oil Shale Semi-Coke to a Flue Gas Sorbent

Energies ◽

10.3390/en11113195 ◽

2018 ◽

Vol 11 (11) ◽

pp. 3195 ◽

Cited By ~ 2

Author(s):

Kathleen Dupre ◽

Emily Ryan ◽

Azat Suleimenov ◽

Jillian Goldfarb

Keyword(s):

Surface Area ◽

Flue Gas ◽

Oil Shale ◽

Gas Adsorption ◽

Fixed Bed ◽

Fixed Bed Reactor ◽

Ex Situ ◽

High Temperature Treatment ◽

Dynamics Modeling ◽

Gas Treatment

The volatility of crude oil prices incentivizes the use of domestic alternative fossil fuel sources such as oil shale. For ex situ oil shale retorting to be economically and environmentally viable, we must convert the copious amounts of semi-coke waste to an environmentally benign, useable by-product. Using acid and acid + base treatments, we increased the surface area of the semi-coke samples from 15 m2/g (pyrolyzed semi-coke) to upwards of 150 m2/g for hydrochloric acid washed semi-coke. This enhancement in porosity and surface area is accomplished without high temperature treatment, which lowers the overall energy required for such a conversion. XRD analysis confirms that chemical treatments removed the majority of dolomite while retaining other carbonate minerals and maintaining carbon contents of approximately 10%, which is greater than many fly ashes that are commonly used as sorbent materials. SO2 gas adsorption isotherm analysis determined that a double HCl treatment of semi-coke produces sorbents for flue gas treatment with higher SO2 capacities than commonly used fly ash adsorbents. Computational fluid dynamics modeling indicates that the sorbent material could be used in a fixed bed reactor to efficiently remove SO2 from the gas stream.

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Effect of Catalyst Synthesis Parameters on the Performance of CO2 Hydrogenation to Methanol over SBA-15 Supported Cu/ZnO-Based Catalysts

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.400.159 ◽

2020 ◽

Vol 400 ◽

pp. 159-169

Author(s):

Sara F.H. Tasfy ◽

Noor Asmawati Mohd Zabidi ◽

Maizatul Shima Shaharun ◽

Duvvria Subbarao

Keyword(s):

Surface Area ◽

Fixed Bed ◽

Fixed Bed Reactor ◽

Bet Surface Area ◽

Methanol Production ◽

Synthesis Conditions ◽

Metal Loading ◽

Synthesis Parameters ◽

Metal Support Interaction ◽

Active Metal

Bimetallic Cu-ZnO-based catalyst were systematically prepared via impregnation technique under controlled synthesis conditions of active metal loading, ratio of active metal Cu:Zn and synthesis pH. The effect of the synthesis condition on the performance of the Cu-ZnO supported catalysts with respect to the hydrogenation of CO2 to methanol in micro-activity fixed-bed reactor at 250°C, 2.25 MPa, and 75% H2/25%CO2 ratio. The synthesized catalysts were characterized by transmission electron microscopy (TEM) and temperature programmed desorption, reduction, oxidation and pulse chemisorption (TPDRO) and the surface area determination was also performed. The results demonstrate that the catalytic structure, activity, and methanol selectivity was strongly affected by the synthesis parameters. Increasing of synthesis pH from 1 to 7 shows better metal particles distribution, Cu desperation of 29%, higher BET surface area as well as Cu surface area, while further increasing on pH revealed on particles agglomeration and weak metal-support interaction. In addition, increasing of the active metal loading from 5 to 15 % resulted in dramatic increase in the conversion of CO2 and methanol production while further increase caused lower catalytic performance. Moreover, catalyst with total loading of 15%, Cu:Zn ratio of 70:30 synthesized at pH of 7 exhibit higher catalytic activity of 14%, methanol selectivity of 92%, and TOF of 1.24×103 s-1 compared with other catalyst prepared under various conditions

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Effect of Cu-Doped ZnO Sorbents for Desulfurization

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.728.335 ◽

2017 ◽

Vol 728 ◽

pp. 335-340

Author(s):

Amphon Nitthaisong ◽

Sumittra Charojrochkul ◽

Sutin Kuharuangrong

Keyword(s):

Surface Area ◽

Monoclinic Phase ◽

Single Phase ◽

Hexagonal Phase ◽

Fixed Bed ◽

Fixed Bed Reactor ◽

Breakthrough Time ◽

Small Grains ◽

Doped Zno ◽

Desulfurization Efficiency

The purpose of this work is to synthesize undoped and Cu-doped ZnO sorbents by citrate-gel method and compare desulfurization efficiency, particularly H2S, at 150°C and 300°C. The undoped ZnO result shows a single phase of hexagonal zincite while the CuO monoclinic phase appeared with ZnO hexagonal phase in Cu-doped compositions (denoted by ZCx where x = mol% of Cu). The microstructure and surface area have been investigated by SEM and BET, respectively. The surface area decreases with the amount of Cu and all of them have a porous structure with small grains. The desulfurization performance of all specimens have been investigated by fixed-bed reactor. The results from breakthrough time indicate ZC20 sorbent has highest sulfur sorption capacity at 300°C. The XRD results show ZnO and CuO in ZC20 can absorb sulfur and completely transform to ZnS, cubic CuS and hexagonal CuS at 300°C.

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Cu-Ni Nanocatalysts in Mesoporous MCM-41 and TiO2 to Produce Hydrogen for Fuel Cells via Steam Reforming Reactions

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1096.161 ◽

2015 ◽

Vol 1096 ◽

pp. 161-168 ◽

Cited By ~ 3

Author(s):

Richard Yeboah Abrokwah ◽

Vishwanath G. Deshmane ◽

Sri Lanka Owen ◽

Debasish Kuila

Keyword(s):

Surface Area ◽

Steam Reforming ◽

Anatase Phase ◽

High Surface ◽

Fixed Bed ◽

Fixed Bed Reactor ◽

Reaction Products ◽

One Pot ◽

Steam Reforming Of Methanol ◽

Mcm 41

We have synthesized mesoporous SiO2(MCM-41) and TiO2encapsulated bimetallic Cu-Ni nanocatalysts using an optimized one-pot hydrothermal procedure. The catalysts were characterized using BET, XRD, TGA-DSC and HRTEM techniques. While bimetallic Cu-Ni/MCM-41catalysts have high surface area- 634-1000 m2/g, Cu-Ni/TiO2yields surface area of 250-350 m2/g depending on the metal loading (5-10 wt%). The XRD studies confirmed a long range ordered structure in Cu-Ni/MCM-41 and the presence of the catalytically active anatase phase in the crystalline Cu-Ni/TiO2. The results from HRTEM studies were consistent with the mesoporosity of both supports. These catalysts were tested for methanol conversion and H2/CO selectivity via steam reforming of methanol (SRM) reactions in a fixed bed reactor. There is a distinct difference in the performance of these two supports. Bimetallic 3.33%Cu6.67%Ni/TiO2catalyst showed an impressive 99% H2selectivity at as low as 150°C and a maximum conversion of 92% at 250 °C but 3.33%Cu6.67%Ni/MCM-41 catalyst did not show any H2selectivity at 150°C and only ~12% conversion at 250°C. The effect of each support and relative metal loadings on the activity and selectivity of the SRM reaction products at different temperatures is discussed.

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Activated Carbon Produced by Pyrolysis of Waste Wood and Straw for Potential Wastewater Adsorption

Materials ◽

10.3390/ma13092047 ◽

2020 ◽

Vol 13 (9) ◽

pp. 2047 ◽

Cited By ~ 7

Author(s):

Katarzyna Januszewicz ◽

Paweł Kazimierski ◽

Maciej Klein ◽

Dariusz Kardaś ◽

Justyna Łuczak

Keyword(s):

Activated Carbon ◽

Surface Area ◽

Activated Carbons ◽

Chemical Activation ◽

Fixed Bed ◽

Fixed Bed Reactor ◽

Physical Activation ◽

Activation Process ◽

Waste Wood ◽

Carbon Production

Pyrolysis of straw pellets and wood strips was performed in a fixed bed reactor. The chars, solid products of thermal degradation, were used as potential materials for activated carbon production. Chemical and physical activation processes were used to compare properties of the products. The chemical activation agent KOH was chosen and the physical activation was conducted with steam and carbon dioxide as oxidising gases. The effect of the activation process on the surface area, pore volume, structure and composition of the biochar was examined. The samples with the highest surface area (1349.6 and 1194.4 m2/g for straw and wood activated carbons, respectively) were obtained when the chemical activation with KOH solution was applied. The sample with the highest surface area was used as an adsorbent for model wastewater contamination removal.

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Adsorptive control of water in esterification with immobilized enzymes: II. Fixed-bed reactor behavior

Biotechnology and Bioengineering ◽

10.1002/(sici)1097-0290(19981120)60:4<445::aid-bit6>3.0.co;2-m ◽

1998 ◽

Vol 60 (4) ◽

pp. 445-453 ◽

Cited By ~ 10

Author(s):

Paul Mensah ◽

John L. Gainer ◽

Giorgio Carta

Keyword(s):

Fixed Bed ◽

Immobilized Enzymes ◽

Fixed Bed Reactor

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Characterization of Novel Sorbents for Mercury Removal at Elevated Temperature

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.656-657.23 ◽

2015 ◽

Vol 656-657 ◽

pp. 23-27

Author(s):

Han Wen Cheng ◽

Ching Tsung Yu

Keyword(s):

Elevated Temperature ◽

Transition Metals ◽

Surface Area ◽

Fixed Bed ◽

Elemental Mercury ◽

Fixed Bed Reactor ◽

Mercury Removal ◽

Bet Surface Area ◽

Precipitation Method ◽

Retention Capacity

The novel carbonate sorbents of Mg–Al–CO3 and (Mg3−x, Cux)–Al–CO3, were synthesized by co-precipitation method with individual nitrate salt of metal ions under alkaline conditions. The synthetic sorbent was characterized by analysis techniques such as BET surface area analysis, X-ray diffraction (XRD), and scanning electron microscopy (SEM). Elemental mercury capture experiments were carried out in a fixed-bed reactor including Hg permeation source, furnace, and Hg analyzer, which was conducted at temperature ranging from 30 to 300 o C. The major results showed that the surface area of material was significantly increased via incorporating Cu2+ into Mg–Al–CO3, accordingly enhancing Hg retention capacity of sorbents. SEM imagines displayed the layer appearance of Mg/Al and Mg/Cu/Al sorbents. Crystalline analysis indicated lamella structure accompanied with metal oxides within materials. Mercury removal tests demonstrated that the breakthrough time increased with temperature by adding transition metals to Mg–Al–CO3 as (Mg3−x, Cux)–Al–CO3. Hg uptake by the (Mg3−x, Cux)–Al–CO3 sorbent rapidly increased with elevated temperature up to 200 o C and reached the maximum capacity of 12.93 μg/g, and then gradually decreased after 300 o C. Surface area and unique properties of transition metals are the reason toward improving Hg capture sorbent. These results represent the feasibility of using such Hg sorbents for elemental mercury removal under elevated temperature conditions, and the detail mechanism is needed to be further studied.

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