NCUT National Centre for Upgrading Technology a Canada Alberta alliance for bitumen and heavy oil research Comparison of the Reactivity of Naphthenic Acids in Athabasca bitumen and San Joaquin Valley Parviz Rahimi, Tomoki Kayukawa, Ryan Rodgers and Teclemariam Alem For presentation at Joint CCQTA/COQA Meeting February 10-11, 2010 New Orleans, LA
Outline Background Comparison of reactivity of NA in gas oil fractions Methods for measuring reactivity Effect of sulfur types on NA corrosion Continuous Fe powder test Separation of Reactive and non-reactive NA Identification/Characterization
Background Athabasca bitumen contains approx. 1wt% organic acids, and that are mostly concentrated in the gas oil fraction These acids can cause corrosion in the refinery There is a wide range distribution of NA in AB Are all NA corrosive? 3
Background - Proposed naphthenic acid corrosion in Athabasca bitumen Two types of naphthenic acids - and (low Mw - bad) and (high Mw good) acids are prohibitive through steric effect
ESI (LRMS) Naphthenic Acids
Relative Abundance Relative Abundance Relative Abundance 100 90 80 70 60 50 40 30 20 10 0 100 90 80 70 60 50 40 30 20 10 0 100 90 80 70 60 50 40 30 20 10 0 Broadband ESI Mass Spectrum of Athabasca Bitumen Mass-Isolated Segment MS 2 : Mass Spectrum Following Dissociation of Mass-Isolated Segment Mass Isolation Window for MS 2 300 600 900 1200 m/z
References 1. Donald F. Smith, Tanner M. Schaub, Parviz Rahimi, Alem Teclemariam,Ryan P. Rodgers, and Alan G. Marshall, Self-Association of Organic Acids in Petroleum and Canadian Bitumen Characterized by Low- and High-Resolution Mass Spectrometry, Energy & Fuels 2007, 21, 1309-1316 2. Donald F. Smith, Parviz Rahimi, Alem Teclemariam, Ryan P. Rodgers, and Alan G. Marshall, Characterization of Athabasca Bitumen Heavy Vacuum Gas Oil Distillation Cuts by Negative/Positive Electrospray Ionization and Automated Liquid Injection Field Desorption Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry, Energy & Fuels 2008, 22, 3118 3125 3. Donald F. Smith, Tanner M. Schaub, Sunghwan Kim, Ryan P. Rodgers, arviz Rahimi, Alem Teclemariam, and Alan G. Marshall Characterization of Acidic Species in Athabasca Bitumen and Bitumen Heavy Vacuum Gas Oil by Negative-Ion ESI FT-ICR MS with and without Acid-Ion Exchange Resin Prefractionation Energy & Fuels 2008, 22, 2372 2378 4. 3- Donald F. Smith, Ryan P. Rodgers, Parviz Rahimi, Alem Teclemariam, and Alan G. Marshall, Effect of Thermal Treatment on Acidic Organic Species from Athabasca Bitumen Heavy Vacuum Gas Oil, Analyzed by Negative-Ion Electrospray Fourier Transform Ion Cyclotron Resonance (FT-ICR) Mass Spectrometry, Energy & Fuels 2009, 23, 314 319
SJVGO (2) FT-ICR mass Spectrometry SJV and AB-SAGD SAGD-HVGO D B E 18 14 10 6 D B E 18 14 10 6 2 20 30 40 50 60 Carbon Number 2 20 30 40 50 60 Carbon Number SJVGO (2) -acid SAGD HVGO-acid D B E 18 14 10 6 2 20 30 40 50 60 Carbon Number Carbon Number Increasing Rel. Abundance (% total) D B E 18 14 10 6 2 20 30 40 50 60
Typical naphthenic acid chemical structures O ( ) n O OH ( ) n OH DBE = 1 R O DBE = 3 R ( ) n OH R O ( ) n OH DBE = 2 DBE= 4
FT-ICR mass Spectrometry SJV and AB-SAGD SJVGO (2) N1 SAGD-HVGO N1 18 18 D B E 14 10 6 2 D B E 14 10 6 2 20 30 40 50 60 20 30 40 50 60 Increasing Rel. Abundance (% total)
FT-ICR mass Spectrometry SJV and AB-SAGD SJVGO (2) N1O2 SAGD-HVGO N1O2 18 18 D B E 14 10 6 2 20 30 40 50 60 Carbon Number D B E 14 10 6 2 20 30 40 50 60 Carbon Number SJVGO -acid N1O2 SAGD-HVGO- acid N1O2 D B E 18 14 10 6 2 20 30 40 50 60 18 D 14 B 10 E 6 2 20 30 40 50 60 Increasing Rel. Abundance (% total)
Effect of temperature on TAN reduction AB-SAGD-HVGO SJV-HVGO 4 TAN, mg KOH/g oil 3 2 1 0 SAGD SJV2 Feed 300 C 350 C 375 C 400 C Temp., C
Effect of temperature on TAN reduction AB-Mined-HVGO SJV-HVGO 5 mg KOH/ g oil 4 3 2 1 SJV2 Mined 0 Feed 300 325 350 375 400 Temp., C
Dehydration mechanism of Naphthenic acids COOH HOOC +H 2 O Thermal -H 2 O O C O O C Autoclave experiments should be carried out in an open system
Possible mechanism of NA size reduction HS R S R HO OH + HO OH R= Petrobras NCUT Collaboration 2010
Condenser Products O 2 DBE 14 12 10 8 6 4 2 Condenser Product at 350 C HE-350 C Condenser Product at 400 C HE- 400 C 14 12 DBE 10 8 6 4 2 Carbon Number 20 30 40 50 60 20 30 40 50 60
Corrosion Mechanism R-COOH + Fe (R-COO) 2 Fe + H 2 (R-COO) 2 Fe +H 2 S 2R-COOH+FeS H 2 S+Fe FeS +H 2 Ye pez, O. On the chemical reaction between carboxylic acids and iron, including the special case of naphthenic acid. Fuel 2007, 86, 1162-1668.
Effect of Sulfur type on corrosion R 2 S=O+2RSH R 2 S+ RSSR + H 2 O R 2 S=O+H 2 R 2 S+ H 2 O Ye pez, O. Influence of different sulfur compounds on corrosion due to naphthenic acid. Fuel 2005, 84, 97-104.
Reactive and non- reactive acids separation Objective Separate Reactive acids and Non-Reactive acids from HVGO fraction Methods Iron Powder Test (IPT) Examine reactivity of acids using iron powder Reactive acids are converted to Iron naphthenates New Acid-IER Separate Reactive acids and Non-Reactive acids from Product of IPT using 2 types of ion exchange resin 6
Issues with Fe Powder test using Batch reactor Water formation Complicates reaction chemistry Decomposition of Iron naphthenate above 300 C Underestimates reactive acids
Experimental Unit Continuous Flow Glass Tube Reactor T Feed Glass beads 2mm Fe Powder -325mesh 15.05g Glass beads 2mm 70mm 316 Stainless Steel 1/ 2 inch *255mmL Product
Reaction Conditions Feed HVGO from Mined, SJV Temperature : 250 ~ 350 o C Flow rate : 0.17 ~ 0.50 cc/min LHSV : 2 ~ 6 h -1 Residence Time : 10 ~ 30 min Fe powder : 5 cc (15 g) N 2 flow rate : 5~10 ml/min Residence Time [min] = Fe powder [cc] / Flow rate [cc/min] LHSV [h -1 ] = 60 / Residence time [min] 6
Iron Powder Test Oil ACID R acid NR Gas oils are contacted with Fe powder in a packed bed reactor in a continuous unit Reactive acids are converted to iron salt 2 R-COOH + Fe (R-COO) 2 Fe + H 2 Iron Powder R-COOH R-H + CO 2 Test Conditions Temperature: Pressure: Residence time: Analyses 250~350 C o Atmosphere 30 min. Product: TAN Gas: H 2, CO 2 8
Reaction Mechanism R-COOH + Fe (R-COO) 2 Fe + H 2 R-COOH Reactive Decarboxylation CO 2 +RH H 2 S+Fe FeS +H 2 (R-COO) 2 Fe +H 2 S 2R-COOH+FeS Ye pez, O. On the chemical reaction between carboxylic acids and iron, including the special case of naphthenic acid. Fuel 2007, 86, 1162-1668.
Effect of temperature on Sulfur and MW Run Temp., C 0 300 325 350 375 400 SJV2 Sulfur MW % wt g/mole 1.33 459 1.36 423 1.36 426 1.29 387 1.14 389 HVGO Sulfur MW % wt g/mole 3.48 345 3.40 333 3.51 338 3.56 337 3.32 343
Reactivity of AB-HVGO 100 90 Non-Reacted Acids 80 Acid Yields (%) 70 60 50 40 Feed : AB-HVGO Press. : Atomospheric Time : 10min Non-Reacted Acid [GAS] Reacted Acid [GAS] Decomposed Acid [GAS] Decomposed Acids 30 20 10 Reacted Acids 0 200 250 300 350 400 Temperature ( o C)
Reactivity of SJV-HVGO 100 90 80 Feed : SJVGO(2) Press. : Atomospheric Time : 30min Acid Yields (%) 70 60 50 40 Non-Reacted Acids Non-Reacted Acid [GAS] Reacted Acid [GAS] Decomposed Acid [GAS] 30 20 Reacted Acids 10 Decomposed Acids 0 200 250 300 350 400 Temperature ( o C)
Results of IPT Athabasca HVGO TAN : 4.29 mg/g SJVGO TAN : 3.47 mg/g Temp. 300 C RT 30 min. Gas Analysis (H 2, CO 2 ) Temp. 300 C RT 30 min. Gas Analysis (H 2, CO 2 ) Product Product TAN : 3.23 mg/g (24.7% ) Non-Reacted Acids: 67.9% Reacted Acids : 28.0% Decomposed Acids: 4.1% TAN : 2.40 mg/g (30.8% ) Non-Reacted Acids: 53.9% Reacted Acids : 41.8% Decomposed Acids: 4.3% 10
Comparison of the reactivity of gas oil fractions at 300 C Feedstocks AB-HVGO SJV-VGO TAN Feedstock mg KOH/g oil 4.3 3.5 TAN Product mg KOH/g oil 3.2 2.4 Reacted ACID (TAN) % 24.7 30.8 Reacted Acid (gas) wt% 28 41.8 Decarboxylation (gas) wt% 4.1 4.3 Non-Reacted Acid (gas) wt% 67.9 53.9
1. Acids Separation 5
Acid-IER Method (Statoil) Oil Acids Selective isolation of carboxylic acids from crude oils using QAE Sephadex A-25 IER (Strong Anion ER) Strong anion ER Acids Oil 11
Acid-IER Method (Statoil) Oil FeNA R acid NR Strong anion ER ACID R acid NR Selective Isolation of Carboxylic Acids from Crude Oils using QAE Sephadex A-25 IER (Strong Anion ER) ER absorbs not only Acids but also FeNA Oil This method can NOT distinguish Reactive Acids and Non-Reactive Acids 12
New Acid-IER Method Oil FeNA R acid NR Weak anion ER Strong anion ER acid NR ACID R Oil Selective Isolation of NA and FeNA from IPT product using 2 types of resins Weak anion ER isolates only Non- Reactive Acids Strong anion ER adsorb FeNAs, and Reactive Acids can be released by formic acids 13
Procedure of Separation Oil ACID R acid NR HVGO Iron Powder Oil FeNA R acid NR IPT Product Weak Anion ER (Amberlyst A-21) Oil : Acid-free fraction ACID R : Reactive Acids acid NR : Non-Reactive Acids FeNA R : Iron Naphthenate acid NR ACID R + Fe FeNA R STEP 1 Iron Powder Test Strong Anion ER (Amberlyst A-26) STEP 2 New Acid-IER ACID R Oil 7
Optimum Quantity of Resin 100 90 80 Feed : Ath. HVGO Oil : 10g Resin : Weak Anion ER Recovery of Acid (%) 70 60 50 40 30 Optimum Too much 20 10 0 Insufficient 0 5 10 15 20 25 30 Resin (g) 14
Optimum Quantity of Resin 50 Exchange Capacity TAN x Oil (mg-koh) 45 40 35 30 25 20 15 10 5 0 Weak Anion ER Calibration Curve Optimum quantities of resin are calculated from this calibration curve 0 5 10 15 20 25 Resin (g) 15
Results of Acids Separation Product TAN : 3.73 mg/g <Expected Yields> Acid-free Oil : 96.67 wt% Non-Reactive Acids: 2.94 wt% Reactive Acids : 0.39 wt% (Calculated from Gas Analysis) acid NR ACID R Oil 2.71 wt% (92% Recovery) 0.32 wt% (82% Recovery) TAN : 0.20 mg/g 96.97 wt% (100.3% Recovery) 16
Summary of Acids Separation Oil ACID R acid NR Oil FeNA R acid NR Oil : Acid-free fraction ACID R : Reactive Acids acid NR : Non-Reactive Acids FeNA R : Iron Naphthenate Iron Powder ACID R + Fe FeNA R STEP 1 Iron Powder Test Anion ER STEP 2 New Acid-IER acid NR ACID R Oil Methods for isolation of Reactive Acids and Non- Reactive Acids were established This method achieves high recovery of Acids and Oil 17
2. Analyses 18
Analytical Methods Gas Chromatography GC Analysis following methylation is often adopted Non-methylated NA doesn t elute from column Liquid Chromatography HPLC enables rapid analysis at low temperature Conducted HPLC analysis according to method of Oil Plus Ltd. [J. Sep. Sci. 2007, 30, 375-380] 19
Methylation of NAs Sample Preparation Methylation of NAs is needed for GC Analyses and LC Analyses Methanol and BF 3 (Catalyst) are conventionally used for methylation [Morrison, W.R. (1964)] R-COOH + MeOH BF3 R-COO-Me + H 2 O 20
Methylation of NAs + Methanol BF 3 65 o C, 3hrs NA in HVGO (Ave. MW = 350) Product (Ave. MW < 100) Chemical bonds were broken Side reactions occurred BF 3 is too strong acid 21
Methylation of NAs Sample Preparation Esterification of NAs is needed for GC Analyses and HPLC Analyses Methanol and BF 3 (Catalyst) are conventionally used for methylation [Morrrison, W.R. (1964)] HCl (50 o C, Overnight) R-COOH + MeOH BF3 R-COO-Me + H 2 O But BF 3 is so strong Lewis acid catalyst, it broke the structure of NA, or caused side reaction Apply an improved methylation method which use HCl as acid catalyst [Christie, W.W. (1993)] This method may not cause above problems! 22
Analytical Results (HPLC) Pure Compounds of Methyl ester (1wt% for each) MV 8000 7000 6000 5000 4000 3000 2000 1000 0 3 4 5 6 7 8 9 Time [min] Conditions: Normal Phase Cyclohexane/DCM = 60 / 40 Refractive Index Detector The performance of separation was good 23
Analytical Results (HPLC) Methylated NAs in Athabasca HVGO MV 5000 4000 3000 2000 Conditions: Normal Phase Cyclohexane/DCM = 60 / 40 Refractive Index Detector 1000 0 3 4 5 6 7 Time [min] An unresolved broad peak was apparent Difficult to identify NAs with HPLC 24
Analytical Results (2D-GC) 2D-GC results Methylated Acids in HVGO Low Polar Acids High Polar Acids 25
Summary of Analyses Conventional methylation method using BF 3 did not work for NAs in HVGO HPLC is useful for analyzing of model compounds, but it did not work for NAs in HVGO 2D-GC following methylation using HCl may prove to be a good solution for analyzing of NAs in HVGO 26
Future Plans Acid Separation Repeat experiments at various conditions and feedstocks Analyses Analyze methylated NAs with 2D-GC TOF MS Identify the type of Reactive acids with FT-ICR MS This Project is continuing in Collaboration between NCUT and JGC 27