Optimum reactor configuration for prevention of gypsum scaling during continuous sulphuric acid neutralization

Adams, Jeffrey F.; Papangelakis, Vladimiros G.

doi:10.1016/j.hydromet.2007.07.016

Cited by 8 publications

(4 citation statements)

References 9 publications

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“…23 However, one serious drawback of the commercialized production process is the use of liquid acid, which is inevitably accompanied by energy-inefficient separa-tion of the catalyst from the reaction mixture or the removal of inorganic salt byproducts such as gypsum by neutralization treatment. 24 Although heterogeneous catalysts such as zeolites, 25,26 Amberlyst-15, 26 and Nafion 27 have been examined as alternative catalysts for furfural production at 413−473 K, such a high-temperature reaction in water generally results in the formation of large amounts of byproducts, 28 which limits the furfural yield to 40%. A combination of Lewis and Brønsted acid catalysts were recently reported to convert xylose into furfural in water at low temperatures.…”

Section: Introductionsupporting

confidence: 65%

“…Furfural can be synthesized from xylose and arabinose by acid-catalyzed dehydration. , Furfural has a wide variety of potential applications as a versatile intermediate for the production of furan derivatives, , fuel additives, , diols and dicarboxylic acids for polyester synthesis, − and hydrocarbons, which is why furfural is industrially produced using H 2 SO 4 as a Brønsted acid catalyst . However, one serious drawback of the commercialized production process is the use of liquid acid, which is inevitably accompanied by energy-inefficient separation of the catalyst from the reaction mixture or the removal of inorganic salt byproducts such as gypsum by neutralization treatment . Although heterogeneous catalysts such as zeolites, , Amberlyst-15, and Nafion have been examined as alternative catalysts for furfural production at 413–473 K, such a high-temperature reaction in water generally results in the formation of large amounts of byproducts, which limits the furfural yield to 40%.…”

Section: Introductionmentioning

confidence: 99%

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Amorphous Nb₂O₅ as a Selective and Reusable Catalyst for Furfural Production from Xylose in Biphasic Water and Toluene

2017

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Aqueous-phase dehydration of xylose into furfural was studied in the presence of amorphous Nb2O5 with water-compatible Brønsted and Lewis acid sites. Nb2O5 was determined as a more active and selective catalyst for xylose dehydration than typical homogeneous Brønsted and Lewis acid catalysts including HCl and Sc(OTf)3, and Nb2O5 converted 93% of xylose with 48% selectivity toward furfural in water at 393 K. No significant loss of the original catalytic activity was observed after Na+-exchange treatment, which indicates that the reaction proceeded only on Lewis acid sites. Isotope-labeling experiments using D2O and xylose suggested that furfural is formed through stepwise dehydration via a highly reactive dicarbonyl intermediate on Nb2O5, whereas typical Lewis acids such as CrCl3 and Sc(OTf)3 convert xylose to furfural in water through hydride transfer and subsequent dehydration via xylulose as a ketose-type intermediate. The difference in the reaction mechanism accounts for the lower activation energy (83 kJ mol–1) with Nb2O5 than those with Sc(OTf)3 and HCl (107–131 kJ mol–1). Continuous extraction of evolved furfural with toluene enabled a large increase in the selectivity toward furfural from 48% to 72% and prevented deactivation of the Lewis acid sites by covering with heavy byproducts, represented by humin.

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Section: Introductionsupporting

confidence: 65%

Section: Introductionmentioning

confidence: 99%

Amorphous Nb₂O₅ as a Selective and Reusable Catalyst for Furfural Production from Xylose in Biphasic Water and Toluene

2017

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“…The neutralization process is carried out in various types of neutralizers in a continuous regime (Adams and Papangelakis 2007;Nam et al 2013). Following the present results, previous studies have demonstrated that a lot of effort has been put in studying the selection of optimal conditions for the neutralization process, for example, determination of an appropriate neutralization reaction time (Yan et al 1999).…”

Section: Introductionmentioning

confidence: 99%

Studies of neutralization reaction induced by rotating magnetic field

et al. 2020

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This study reports on research results in the field of the neutralization process (weak acid-strong base) under the action of a rotating magnetic field. The main objective of this paper is to present the possibilities of this process application to obtain the mixing time. The results show that the applied magnetic field had a strong influence on the analyzed process. Enhancement of the mixing process under the action of the rotating magnetic field may be obtained using particles with magnetic properties. It is shown that the time, after which the equivalence point of the neutralization process is reached, may be considered a parameter to describe the mixing process. Based on the proposed definition of the mixing time, the dimensionless correlation for the relationship between the mixing number and the Reynolds number is presented. Furthermore, results for the realization of the neutralization process with the application of the rotating magnetic field and magnetic particles are also discussed.

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“…Although there exist several studies on crystallization of sparingly soluble salts on the heat-exchange surface and scaling on nanofilters in desalination units [13][14][15][16][17][18][19], very little work has been done for the investigation of scale formation on pipe walls and cooling systems. Gypsum or calcium sulfate dihydrate is a dominant scalant in most industrial water systems and has been the subject of various investigations [6,11,12,[20][21][22][23][24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Effects of Process Parameters on Gypsum Scale Formation in Pipes

2011

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Scaling often leads to a series of technical and economical problems in industrial plants and equipments by blocking water flow in pipes or limiting heat transfer in heat exchangers. While most contemporary studies are focusing on crystallization at heat-exchanger surfaces and scaling on nanofilters in desalination plants, very little work has been done investigating scale formation on pipe and vessel walls. A comprehensive investigation of the effects of various process parameters in controlling the formation of calcium sulfate scale in pipes was undertaken. Supersaturation ratio, run time, and operational hydrodynamics were altered systematically to determine their influence on the scale growth rate. The results confirmed that the deposition of gypsum on pipe walls was significantly affected by these process parameters.

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Optimum reactor configuration for prevention of gypsum scaling during continuous sulphuric acid neutralization

Cited by 8 publications

References 9 publications

Amorphous Nb₂O₅ as a Selective and Reusable Catalyst for Furfural Production from Xylose in Biphasic Water and Toluene

Amorphous Nb₂O₅ as a Selective and Reusable Catalyst for Furfural Production from Xylose in Biphasic Water and Toluene

Studies of neutralization reaction induced by rotating magnetic field

Effects of Process Parameters on Gypsum Scale Formation in Pipes

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Optimum reactor configuration for prevention of gypsum scaling during continuous sulphuric acid neutralization

Cited by 8 publications

References 9 publications

Amorphous Nb2O5 as a Selective and Reusable Catalyst for Furfural Production from Xylose in Biphasic Water and Toluene

Amorphous Nb2O5 as a Selective and Reusable Catalyst for Furfural Production from Xylose in Biphasic Water and Toluene

Studies of neutralization reaction induced by rotating magnetic field

Effects of Process Parameters on Gypsum Scale Formation in Pipes

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Product

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Amorphous Nb₂O₅ as a Selective and Reusable Catalyst for Furfural Production from Xylose in Biphasic Water and Toluene

Amorphous Nb₂O₅ as a Selective and Reusable Catalyst for Furfural Production from Xylose in Biphasic Water and Toluene