Catalytic activity recovery of spent alumina: A case study of Awash Melkassa Chemical Factory
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Abstract
Hydrogen peroxide was one of the major bleaching chemical produced in Awash Melkassa
Chemical Factory. The auto-oxidation anthraquinone process route utilizing the working
solution as a working media used to produce hydrogen peroxide. In this process route,
activated alumina was used for converting inactive byproduct of THAQE into active form
of THAQ and EAQ through regeneration mechanism. However, continuous usage of
alumina resulted in losing of catalytic activity and unable to regenerate inactive THAQE.
Thus, catalytic activity recovery of spent deactivated alumina by regeneration method was
a subject of study. The deactivated alumina regeneration was carried out by Soxhlet
solvent extraction followed by caustic treatment. In Soxhlet solvent extraction, methanol,
ethyl acetate and the mixture of methanol and ethyl acetate were used to assess the
removal of polar organic compounds contained in deactivated alumina. The highest
organic removal efficiency was observed at 69.05% when mixture of methanol and ethyl
acetate was used for extraction. Further treatment of alumina was carried out using
caustic treatment to remove the remaining adsorbed organic components and to modify the
alkaline composition. The effect of caustic treatment conditions (temperature,
concentration and contact time) was investigated to observe the basic sites of alumina. The
highest basicity (2.19 mmol HCl/gm of catalyst) was observed at NaOH concentration of
3% w/w, temperature 70 oC and contact time of 2.5 hours. The AAS analysis also showed
that the content of Na2O in the regenerated alumina was increased to 0.42% as compared
to fresh alumina (<0.01%) that implied the improvement of catalytic activity. Based on
XRD analysis, the XRD pattern indicated that there was no structural change observed in
the regenerated alumina caused by NaOH loading since it had similar diffraction peaks
and intensities as spent and fresh alumina. The BET analysis showed that the specific
surface area of regenerated alumina was 507.009 m2
/gm indicated the higher catalytic
activity as compared to the spent alumina (337.762 m
2
/gm). The performance test
indicated that 18.9% and 13.75% of THAQE conversion was obtained by regenerated
alumina and reused alumina respectively. As compared to fresh alumina of 100%
performance, 72.81% and 52.99% of THAQE was converted to active quinones using
regenerated alumina and reused alumina respectively. Therefore, regenerated alumina
could be used instead of fresh alumina as a catalyst and an adsorbent for working solution
regeneration for more than two times.
Hydrogen Peroxide Was One Of The Major Bleaching Chemical Produced In Awash Melkassa Chemical Factory. The Auto-Oxidation Anthraquinone Process Route Utilizing The Working Solution As A Working Media Used To Produce Hydrogen Peroxide. In This Process Route, Activated Alumina Was Used For Converting Inactive Byproduct Of Thaqe Into Active Form Of Thaq And Eaq Through Regeneration Mechanism. However, Continuous Usage Of Alumina Resulted In Losing Of Catalytic Activity And Unable To Regenerate Inactive Thaqe. Thus, Catalytic Activity Recovery Of Spent Deactivated Alumina By Regeneration Method Was A Subject Of Study. The Deactivated Alumina Regeneration Was Carried Out By Soxhlet Solvent Extraction Followed By Caustic Treatment. In Soxhlet Solvent Extraction, Methanol, Ethyl Acetate And The Mixture Of Methanol And Ethyl Acetate Were Used To Assess The Removal Of Polar Organic Compounds Contained In Deactivated Alumina. The Highest Organic Removal Efficiency Was Observed At 69.05% When Mixture Of Methanol And Ethyl Acetate Was Used For Extraction. Further Treatment Of Alumina Was Carried Out Using Caustic Treatment To Remove The Remaining Adsorbed Organic Components And To Modify The Alkaline Composition. The Effect Of Caustic Treatment Conditions (Temperature, Concentration And Contact Time) Was Investigated To Observe The Basic Sites Of Alumina. The Highest Basicity (2.19 Mmol ?Hcl/Gm Of Catalyst) Was Observed At Naoh Concentration Of 3% W/W, Temperature 70 Oc And Contact Time Of 2.5 Hours. The Aas Analysis Also Showed That The Content Of Na2o In The Regenerated Alumina Was Increased To 0.42% As Compared To Fresh Alumina (<0.01%) That Implied The Improvement Of Catalytic Activity. Based On Xrd Analysis, The Xrd Pattern Indicated That There Was No Structural Change Observed In The Regenerated Alumina Caused By Naoh Loading Since It Had Similar Diffraction Peaks And Intensities As Spent And Fresh Alumina. The Bet Analysis Showed That The Specific Surface Area Of Regenerated Alumina Was 507.009 M2/Gm Indicated The Higher Catalytic Activity As Compared To The Spent Alumina (337.762 M2/Gm). The Performance Test Indicated That 18.9% And 13.75% Of Thaqe Conversion Was Obtained By Regenerated Alumina And Reused Alumina Respectively. As Compared To Fresh Alumina Of 100% Performance, 72.81% And 52.99% Of Thaqe Was Converted To Active Quinones Using Regenerated Alumina And Reused Alumina Respectively. Therefore, Regenerated Alumina Could Be Used Instead Of Fresh Alumina As A Catalyst And An Adsorbent For Working Solution Regeneration For More Than Two Times.
Hydrogen Peroxide Was One Of The Major Bleaching Chemical Produced In Awash Melkassa Chemical Factory. The Auto-Oxidation Anthraquinone Process Route Utilizing The Working Solution As A Working Media Used To Produce Hydrogen Peroxide. In This Process Route, Activated Alumina Was Used For Converting Inactive Byproduct Of Thaqe Into Active Form Of Thaq And Eaq Through Regeneration Mechanism. However, Continuous Usage Of Alumina Resulted In Losing Of Catalytic Activity And Unable To Regenerate Inactive Thaqe. Thus, Catalytic Activity Recovery Of Spent Deactivated Alumina By Regeneration Method Was A Subject Of Study. The Deactivated Alumina Regeneration Was Carried Out By Soxhlet Solvent Extraction Followed By Caustic Treatment. In Soxhlet Solvent Extraction, Methanol, Ethyl Acetate And The Mixture Of Methanol And Ethyl Acetate Were Used To Assess The Removal Of Polar Organic Compounds Contained In Deactivated Alumina. The Highest Organic Removal Efficiency Was Observed At 69.05% When Mixture Of Methanol And Ethyl Acetate Was Used For Extraction. Further Treatment Of Alumina Was Carried Out Using Caustic Treatment To Remove The Remaining Adsorbed Organic Components And To Modify The Alkaline Composition. The Effect Of Caustic Treatment Conditions (Temperature, Concentration And Contact Time) Was Investigated To Observe The Basic Sites Of Alumina. The Highest Basicity (2.19 Mmol ?Hcl/Gm Of Catalyst) Was Observed At Naoh Concentration Of 3% W/W, Temperature 70 Oc And Contact Time Of 2.5 Hours. The Aas Analysis Also Showed That The Content Of Na2o In The Regenerated Alumina Was Increased To 0.42% As Compared To Fresh Alumina (<0.01%) That Implied The Improvement Of Catalytic Activity. Based On Xrd Analysis, The Xrd Pattern Indicated That There Was No Structural Change Observed In The Regenerated Alumina Caused By Naoh Loading Since It Had Similar Diffraction Peaks And Intensities As Spent And Fresh Alumina. The Bet Analysis Showed That The Specific Surface Area Of Regenerated Alumina Was 507.009 M2/Gm Indicated The Higher Catalytic Activity As Compared To The Spent Alumina (337.762 M2/Gm). The Performance Test Indicated That 18.9% And 13.75% Of Thaqe Conversion Was Obtained By Regenerated Alumina And Reused Alumina Respectively. As Compared To Fresh Alumina Of 100% Performance, 72.81% And 52.99% Of Thaqe Was Converted To Active Quinones Using Regenerated Alumina And Reused Alumina Respectively. Therefore, Regenerated Alumina Could Be Used Instead Of Fresh Alumina As A Catalyst And An Adsorbent For Working Solution Regeneration For More Than Two Times.