Originally appeared in: Jan/Feb 2020, pgs 17-22. SPECIAL FOCUS: TREATING TECHNOLOGY Used with permission.

Cost-effective, modular technologies for , and NGL treating

D. B. ENGEL, S. WILLIAMS, H. BURNS and R. CROWE, Exion Systems, The Woodlands, Texas

Hydrocarbon processing plants often Merichem’s Thiolex process utilizes a for example, mercaptans have a particu- encounter challenges with feedstocks con- chemical mechanism similar to the UOP larly foul odor. The change from a more taining high levels of mercaptans, which Merox process, with caustic extraction electronegative atom (oxygen) to sulfur concentrate in condensates and regeneration via a catalytic oxidation also imparts to mercaptans a more acidic and NGL when the mercaptans are not stage to separate, transform and remove character compared to their alcohol coun- removed upstream by the acid gas removal mercaptans. It also has a liquid waste terparts due to the sulfur atom’s stabiliz- unit (AGRU) or molecular sieve unit. stream (dimethyl disulfide) that must be ing effect. Mercaptans, however, are only While (H2S), as well as disposed of. This process system carries slightly acidic, and this acidity is reduced carbon dioxide (CO2), are removed by high capital expenses, similar to the UOP as the molecular weight of the mercaptan amine treating units, most will remove Merox system. Both systems are also sub- increases. FIG. 1 shows the molecular for- little to no mercaptans. Only when physi- ject to caustic waste disposal, and many mula and structural 3D model for one of cal solvents are used is removal possible.1,2 systems use a bleed and feed of fresh caus- the most common mercaptan contami- When NGL or condensates recovered tic to maintain a high pH. nants, methyl mercaptan (also named in gas processing contain high levels of Due to limited technologies to cost- methylthiol or ). mercaptans, off-spec fractionated prod- effectively treat hydrocarbon streams Relative to alcohols, mercaptans are ucts can occur, the hydrocarbon can have containing low-tonnage mercaptans and more acidic. Butyl mercaptan has a pKa of a negative odors and the value of the hy- H2S, one company set a goal to develop a 10.5 compared to 15 for butanol. Phenol drocarbon can be decreased, resulting in small and flexible system to address those mercaptan has a pKa of 6 compared to 10 loss of revenue. Additionally, the NGL, needs. As an alternative for large-scale for phenol. Therefore, mercaptanate (or condensate or its fractionated products systems, this company has developed a thiolate) salts can be created by treating often will not meet total sulfur or will fail systemb that is specifically designed to mercaptans with alkali hydroxides, such a quality test, such as a copper strip cor- treat hydrocarbon streams with less than 1 as or caustic. In fact, rosion test. tpd of mercaptans. These systems can be caustic is a common removal method for The two most commonly used tech- skid-mounted, are compact and require mercaptans in liquid streams (water and nologies for mercaptans removal are a minimal footprint. The technology has ). The chemical equations UOP’s Merox and Merichem’s Thiolex a chemical injection stage, followed by for the reaction of mercaptans (R-SH) systems. UOP’s Merox process utilizes a a proprietary contacting and separation and alcohols (R-OH) with sodium hy- proprietary catalyst, known simply as the process. The proprietary chemical con- droxide are indicated in Eqs. 1 and 2: Merox catalyst, along with heat and air to verts H2S, carbonyl sulfide (COS) and oxidize mercaptans to a disulfide in the mercaptans into stable, non-hazardous R-SH + NaOH → NaS-R + H2O regeneration stage. and water-soluble compounds. The spent (Forward reaction) (1)

The Merox process is a demonstrated chemical is stable and easily disposed of R-OH + NaOH } NaO-R + H2O and proven process for mercaptans re- by any of several methods, depending on (Equilibrium reaction) (2) moval. However, the large capital expense the plant infrastructure. for these systems typically makes them In addition, mercaptans have weaker viable only for large-scale applications. H2S, mercaptans and mercaptans intermolecular forces. They show little as- The Merox process is generally used for removal. Mercaptans, or , are a sociation by hydrogen bonding with water large-scale applications where caustic group of sulfur-based components that regeneration is required to make the op- are found in many hydrocarbon streams, erating economics viable. In addition, as mainly as an impurity. Mercaptans are part of the Merox process, a waste liquid similar to alcohols, but with the oxygen stream (dimethyl disulfide) is formed af- atom replaced by a sulfur atom. This ter caustic regeneration. Therefore, provi- change confers to mercaptan molecules sions must be taken for its proper disposal distinct chemical and physical properties. FIG. 1. Molecular structure (left) and molecular or reprocessing. Organoleptic properties are also affected; model (right) of methyl mercaptan.

Gas Processing | JANUARY/FEBRUARY 2020 17 SPECIAL FOCUS: TREATING TECHNOLOGY

From health, safety and process perspectives, cases, an odor release occurs. In some cas- es, the spent or rich caustic can be regener- the removal of mercaptans is often necessary. ated using a catalytic process and oxygen. Some mercaptans present strong odors. For this The oxygen regenerates the rich caustic so that it can be reused in the process; how- reason, mercaptans are used as odorizers in ever, it also produces a secondary disulfide consumer and commercial natural gas to alert oil (DSO) byproduct. Disulfides (also called red oil) are water-immiscible mate- to gas leaks. rials that can be a challenge for disposal in a gas plant. The chemical reactions for the molecules or among themselves. Mercap- lead to copper strip test failures under regenerative caustic removal of mercap- tans have lower boiling points and are less certain conditions. Mercaptans can nega- tans are indicated in Eqs. 5 and 6: soluble in water and other polar solvents tively affect catalysis and solid adsorption than alcohols of similar molecular weight. beds, such as silica gel or alumina, by com- 2 R-SH + 2 NaOH → 2 NaS-R + Mercaptans will hence have a higher-equi- peting for access to the same active sites. 2 H2O (Extractor reaction (5) librium vapor pressure and will be more Mercaptans removal is also necessary with excess NaOH) soluble in hydrocarbon phases. for reducing sulfur emissions, as com- 4 NaS-R + O2 + 2 H2O → Some mercaptans are also gaseous at bustion and emissions of mercaptans- 2 R-S-S-R (water immiscible ambient conditions in comparison to their containing compounds will lead to SOx DSO) + 4 Na+ + 4 OH– (6) oxygen analogues, due to their lower boil- formation. Mercaptans removal can be (Regeneration) ing point. One example is methyl mer- accomplished by a number of methods. captan (gas) in comparison to methanol The most common method utilized to- where R = hydrocarbon group. (liquid). The electronic configuration of day is the reaction with caustic (sodium Alternative products were developed mercaptans (namely the presence of d-or- hydroxide), shown earlier. Oxidation by especially for mercaptans removal. The bitals in sulfur atoms) provides them with a strong oxidant reagent (such as sodium concept was to use a nonregenerative highly interactive properties with many hypochlorite, oxygen and hydrogen per- mercaptans removal method where the surfaces (especially metals). This interac- oxide, among others) has also been used. waste or byproduct can be easily treated tion is the basis of some of the common The chemical reactions for mercaptans at low cost. This not only minimizes cap- metal surface friction reducers. Sulfur oxidation are indicated in Eqs. 3 and 4: ital costs but also reduces any post-treat- molecules can also serve in many instances ment costs. The reaction pathway does as metal ion chelants and metal stabilizers. 2 R-SH + ½ O2 → R-S-S-R + H2O not involve the use of caustic and elimi- From health, safety and process per- (Oxidation by oxygen) (3) nates the need for secondary treatments, spectives, the removal of mercaptans is R-SH + 3 H O → R-SO H such as regeneration of spent caustic or often necessary. Some mercaptans present 2 2 3 spent caustic disposal. The chemicalc is a + 3 H2O (Oxidation (4) strong odors and can cause serious disrup- by hydrogen peroxide) specialized polyhydric alcohol molecule, tions to daily life. In fact, humans are high- stabilized by hydroxyl materials, that ly sensitive to mercaptans at very low lev- Other methods for mercaptans remov- enables the removal of H2S, mercaptans els. For this reason, mercaptans are used al from hydrocarbon streams are available, and COS. The general chemical equa- as odorizers in consumer and commercial including oxidation using ozone, biologi- tion for the reaction with mercaptans is natural gas to alert to gas leaks. Some mer- cal removal processes, catalytic decom- shown in Eq. 7: captans can cause corrosion, and often position, adsorption into solid beds (i.e., R-SH + CA → R-S-S-R + functionalized activated carbon) and spe- –2 R-S-SO-R + R-R + SO4 + (7) Treated hydrocarbon stream cialized solvents. However, only the latter H O (Oxidative coupling) two methods are commonly used in the 2 Extractor Caustic and disulfides industry. The use of sodium hydroxide for where R-S-SO-R = sulfoxide species Excess air mercaptans removal is perhaps the most (water soluble and does not affect the common worldwide. process). Disulfides Air The reaction with caustic is effective, The reactions show that water, sulfate Oxidizer –2 Feed but is also a reversible equilibrium. So- (SO4 ) and other oxidized components hydrocarbon dium hydroxide is readily available at low are products of the reaction. The water- stream Disulfide cost. Non-regenerative caustic treatment soluble sulfate ion is removed from the separator produces a spent caustic stream that must condensate in the aqueous chemical Regenerated caustic be treated or managed properly. Regen- phase. The chemical additive (CA) is de- Catalyst injection erative caustic treatment produces disul- signed for use with process equipment, fide oil and a waste caustic bleed. FIG. 2 such as a phase separator downstream of Rich caustic shows a typical regenerative caustic mer- the injection point. The challenge was captans removal process. to create a specialized system to oper- FIG. 2. General regenerative caustic The use of caustic for mercaptans re- ate with high efficiency and impart flex- mercaptans removal process. moval causes high salt content. In many ibility for its use. The developed systemb

18 JANUARY/FEBRUARY 2020 | GasProcessingNews.com SPECIAL FOCUS: TREATING TECHNOLOGY has a low capital cost relative to other mercaptans removal units in the indus- try today. The system also has a much smaller footprint, shorter delivery times and can be designed as a modular system, if necessary. The process can provide to- tal filtration of the liquid hydrocarbon to be treated to protect the contactor from fouling. A chemical injection point was established for the chemistry, followed by a mixing and contacting stage for mass transfer and for enabling the reaction to occur more effectively. The system is also highly effective for treating the liquid hy- drocarbon, as well as for removing water emulsions and water-soluble impurities.

System validation protocols. A gas plant near Alberta, Canada was selected b to validate the technology. The plant FIG. 3. Miniaturized systemb used for mercaptans removal validation. required a cost-effective solution for the removal of low-molecular-weight mercap- tans (C1–C3) present in a stabilized con- TABLE 1. Composition of the stabilized condensate stream densate stream. The facility was required Component Mole fraction Mass fraction Liquid volume fraction to meet a mercaptans specifications for H 0 0 0 condensate below 175 mg/kg to meet a 2 future pipeline specification. The average He 0 0 0 levels of C1–C3 mercaptans did not, how- N2 0.0003 0.0001 0.0001 ever, meet the required specifications. CO 0 0 0 To determine if the devised system 2 H S 0 0 0 was feasible for mercaptans removal, an 2 onsite test was performed using a min- C1 0.0027 0.0004 0.001 iaturized unit. The unit was designed to C2 0.0004 0.0001 0.0002 test any liquid hydrocarbon stream up to C 0.0026 0.0011 0.0015 5 gpm. This article outlines the field vali- 3 i-C 0.007 0.0038 0.0048 dation protocols and performance results 4 for mercaptans removal in a hydrocarbon n-C4 0.041 0.0222 0.0273 condensate stream. The onsite process- i-C5 0.1216 0.0818 0.0939 ing of a stabilized condensate slipstream, n-C 0.1705 0.1146 0.1305 using a miniaturized unit, along with the 5 C 0.1802 0.1447 0.1565 injection of a proprietary chemicalc to re- 6 move the mercaptans, followed by a wa- C7 0.4737 0.6312 0.5842 ter wash stage, is shown in FIG. 3. Total 1 1 1 The stabilized condensate composi- tion at the site is shown in TABLE 1. The inlet concentrations of mercaptans are TABLE 2. Inlet concentrations of mercaptans in the untreated condensate stream presented in TABLE 2. The flow, tem- Mercaptan concentrations, mg/kg or ppmw perature and pressure of the condensate C SH 57.1 C SH 369.6 C SH 845.8 C SH 545.5 stream at the moment of the system on- 1 3 5 7 C SH 535.9 C SH 407.7 C SH 627.4 site validation were nearly 2,000 bpd, 2 4 6 Total 3,389.1 approximately 270°F and approximately 100 psig, respectively. system, including the injection points for connecting to the process, the propri- The selected slipstream point for the the chemical and water, valve arrange- etary chemical,c reverse-osmosis-quality condensate was located at the outlet of the ment, contactor/extractor, water wash and water, condensate sampling cylinders stabilizer unit prior to cooling and at high effluent streams. The schematic in FIG. 4 is and a gas chromatograph equipped for temperature. The miniaturized system consistent with the image shown in FIG. 3. mercaptans detection and quantifica- was assembled, using the same treatment The materials used for the onsite tion. Condensate sampling was done up- configuration as a full-size system. FIG. 4 validation test included the miniatur- stream and downstream of the system, as shows the schematic of the miniaturized ized system, stainless steel tubing for shown in FIG. 4.

Gas Processing | JANUARY/FEBRUARY 2020 19 SPECIAL FOCUS: TREATING TECHNOLOGY

High-pressure High-pressure 1,000 injection pump injection pump 900 Outlet Additive Water 800 700 600 500 DP DP 400 P captans, ppmw Untreated Treated 300 hydrocarbon hydrocarbon Me r 200 100 Contactor/ Water 0 extractor wash 0.0 0.5 1.0 1.5 Sample Sample stage Sample Additive mole ratio valve valve valve no. 1 no. 2 no. 3 FIG. 5. Removal of mercaptans at the outlet Aqueous Aqueous as a function of the chemical additive phase phase collection collection concentration, mol/mol.

FIG. 5. The plots reflect the concentration FIG. 4. Schematic of the miniaturized systemb for field deployment and testing. at the outlet of the extractor (downstream of the water injection). The removal rates TABLE 3. Chromatographic equipment used for mercaptans analysis of C1–C3 mercaptans were plotted, as these were the mercaptans of significance Gas chromatograph Column Detector for the pipeline specification. The FIG. 5 Agilent 6890N SAS (proprietary column) Thermal conductivity, TCD y axis shows the removal of mercaptans as Agilent 7890A PlotQ Thermal conductivity, TCD a function of the chemical additive con- centration in the mole ratio. Mole ratios Agilent 7890A GasPro Flame photometric, FPD of 0.5, 1 and 1.5 moles of active chemi- cal per mole of total mercaptans were in- TABLE 4. Effluent water analysis from the miniaturized test system jected during sampling events, equivalent to 3,000, 4,500 and 6,000 ppmw, respec- Ion Concentration (mg/l) Ion Concentration (mg/l) tively, of the condensate stream. Aluminum 15 Nitrate 1.55 The chemical additivec significantly 0.05 Nitrile > 0.06 reduces the mercaptan levels in the con- densate stream. The removal increases as Calcium 20.1 o-Phosphate 1.41 the concentration of additive increases. Chloride 36,240 Potassium 12,200 The test protocol using the miniaturized Fluoride < 0.04 Sodium 9,860 system indicates that a 1 mole ratio is suf- Iron 0.979 Sulfate 421.3 ficient to lower the C1–C3 mercaptans lev- els to below 200 ppmw. Mercaptans levels Magnesium 0.251 Zinc 0.1 are lowered more effectively for C1–C3 Manganese 0.066 pH 10.2 mercaptans, as the smaller-size mercap- tans react faster with the chemical addi- tive (reaction kinetics or by better molec- Test conditions and procedures. The injection was initiated was allowed before ular diffusion and mixing). It is, therefore, temperature of the condensate was ap- sampling for each data point. Local re- conceivable that the chemical injection proximately 300°F as measured at the verse osmosis water was used to dilute the concentration and injection rates can be stabilizer outlet, and a slipstream flow- chemicalc formulation for injection. The optimized with the objective to remove rate of 1 gpm–1.7 gpm of condensate was method for analyzing mercaptans was certain mercaptans at target levels. maintained from the stabilizer outlet into performed using a gas chromatograph the system. The testing setpoints used and by introducing calibration samples Residual water analysis. The injected were varied during testing to optimize the for proper reference. A calibration curve water used was from a reverse-osmosis mercaptans removal efficiency. A 65-ml/ was constructed for every mercaptan ana- plant installed at the facility. The effluent- min injection rate (chemical/water), or lyzed. The results were initially obtained injected water from the miniaturized sys- approximately 1%–1.7% of the total con- in ppm on a volume basis and then fur- tem was collected and further analyzed densate flow treated, was generally used. ther converted to ppmw. TABLE 3 presents for common anions and cations. The wa- The chemical/water injection was at the various chromatographic equipment ter analysis was performed using an ion room temperature (21°C). Samples were used in the quantification of mercaptans. chromatography (IC) apparatus. TABLE 4 taken at the inlet and outlet of the system shows the results for the water analysis (for for analysis, using specialized cylinders to Mercaptans removal performance. a 1-mole ratio additive injection). maintain sample integrity. The data for the accumulated mercaptans It can be observed from analysis that All mercaptans analysis was performed concentration were plotted as a function the effluent water had increased salt con- onsite. A 10-min run time after chemical of the additive injection concentration in tents in terms of chlorides and sodium,

20 JANUARY/FEBRUARY 2020 | GasProcessingNews.com SPECIAL FOCUS: TREATING TECHNOLOGY which is typically found in natural forma- tion waters (also known as connate water). In addition, the presence of calcium, mag- nesium, phosphate and nitrate is indica- tive of components present in produced water. The only two components originat- ing from the chemical additive are sulfate and potassium. These components are generally simple to dispose of, as they are also present in natural waters. The pres- ence of iron was interpreted as being from the naturally occurring water formation or as a byproduct of pipeline corrosion.

Scale-up considerations. The conden- sate stream presented high solids content and fouled the miniaturized system con- tactor/extractor more rapidly than an- ticipated. This aspect should be verified in any future condensate treating applica- tion to allow for proper feed condition- FIG. 6. Full-scale systemb for condensate treating. ing, when necessary. A number of aspects were deemed worth indicating. Operationally, it is im- portant to mention that the chemistry performed effectively for mercaptans re- moval to the required levels. The results were further validated by independent onsite mercaptans testing, using special- ized sampling cylinders and chromato- graphic techniques. Other important ar- eas to consider are: • The best chemical additivec dosage is between 1 mole and 1.5 mole ratio (for the application tested) • Higher temperatures are beneficial for faster chemical reaction rates • Condensate filtration upstream of the chemical injection is needed to protect the system from a high level of suspended particulates • Lower-molecular-weight mercaptans are more effectively removed • Sampling cylinders are critical for condensate sampling to FIG. 7. Full-scale systemb for butane treating. maintain sample integrity, if testing low-boiling-point contaminants. process guarantee was to treat the con- ly, for the associated inlets. The chemi- Full-scale systems. After the testing densate to a level of 175 ppmw of C1–C3 cal treatment was adjusted to target 150 and validation work was completed as mercaptans. ppmw to allow for variations in the feed. described, a full-scale systemb was de- In October 2018, the system under- signed, fabricated and installed. That went commissioning and startup. During Full-scale butane system. Another system is shown under construction in the startup phase, the operation was tuned treatment skid was installed at a fraction- FIG. 6. for optimal performance and to execute ation plant that was experiencing quality The full-scale system was designed to the process guarantee. The condensate issues with its butane. The butane stream process flowrates up to 12,000 bpd, with feed contained mercaptan levels from 413 was required to pass specifications for inlet mercaptan levels of up to 644 ppmw ppmw–436 ppmw. The treated effluent hydrocarbon corrosion measured by the and 20 ppmw of H2S intermittently. The was 88 ppmw and 119 ppmw, respective- copper strip test. As done previously with

Gas Processing | JANUARY/FEBRUARY 2020 21 SPECIAL FOCUS: TREATING TECHNOLOGY

2 Kohl, A. L. and R. Nielsen, Gas Purification, 5th Ed., Gulf Publishing, Houston, Texas, September 1997.

DAVID ENGEL has more than 25 yr of industrial experience in a variety of chemical engineering and chemistry areas. He is the inventor in 22 US patents and the author of a number of technical and scientific papers. Dr. Engel has developed business and technology for Eastman Kodak, Eli Lilly, Pentair, General Electric and Sulphur Experts worldwide. He has specialized in chemical engineering, process chemistry, optimization and contaminant removal technologies. Dr. Engel is the Managing Director of Nexo Solutions and the Technology Leader for Exion Systems. He holds a BS degree in industrial chemistry, an MS degree in chemistry and a PhD in organic chemistry. He is also Six Sigma and Project Management certified. Dr. Engel is President of the American Filtration Society, b FIG. 8. Copper strip test results when using the system for butane treating. The untreated Southwest Region; and a member of the Gas copper strip test (3b result) is shown at right, and the treated copper strip test result (1b) Processors Association Technical Section M, in is shown at left. addition to a member of the boards of directors at several companies.

TABLE 5. Butane treatment for low mercaptan effluent SCOTT WILLIAMS is a Process Engineer at Amine Optimization. Butane flowrate, Combined methyl and Treated outlet, He has industry experience in a Chemistry bpd ethyl mercaptan, ppmw ppmw number of projects in oil and gas, petrochemical, chemical and water Exion LT A900 1013 27.8 0.8 treatment applications. As part Exion LT A900 1087 41.9 3.6 of the Amine Optimization engineering group, Mr. Williams is responsible Exion LT A700 992 58.2 4.7 for technical design and solutions development in engineering and technology applications. He also Exion LT A700 893 131.3 4.7 provides support for analytical and specialized service projects. His recent work has been focused on the condensate application, a field trial tans in the butane to very low levels. While amine unit contamination control, process stability and energy reduction. Mr. Williams holds a BS degree was conducted with a miniature system to low levels of mercaptans were not origi- in chemical and biological engineering from the prove that the process could treat the bu- nally part of the treatment design specifi- University of Colorado at Boulder. tane to the plant’s quality specifications. cation, the facility asked if a 5-ppmw level The stream showed the presence of of combined methyl and ethyl mercaptan HEATH BURNS is an Engineer and c General Manager of Exion Systems several sulfur-based contaminants, such could be obtained. The chemical was LLC. He has been working in the as mercaptans, sulfides, disulfides and reformulated and tested at the full-scale oil and gas and process industries for 20 yr. Mr. Burns' experience sometimes H2S. The design flowrate of unit. New chemistries were trialed over includes manufacturing, research butane was 1,750 bpd, with an average several weeks in June 2019, with samples and development, pilot testing, operational rate of 1,000 bpd. The sulfur- collected at the inlet and outlet. engineering design and business development. based contaminants varied in concen- The samples were analyzed using a gas He has extensive field experience in developing tration from 10 ppmw–100 ppmw. The chromatograph with a sulfur chemilumi- methods for analyzing, troubleshooting and mitigating various process contamination issues. system shown in FIG. 7 is the skid system nescence detector set up for liquid injec- He also consults for Nexo Solutions and Amine d installed for the butane. tion. One chemistry proved to be the Optimization. Mr. Burns holds a BS degree in The treatment effect of the system best treatment for achieving low effluent Mechanical Engineering Technology from for the butane is shown in FIG. 8. In this mercaptan levels. This chemistry showed Texas A&M University. case, the butane production (feed butane that, upon spikes of the methyl and ethyl RYAN CROWE is the Vice President to the system) yielded a copper strip test mercaptans, the required 5-ppm specifi- of Business Development for Exion Systems LLC. He started result of 3b. The reddish color of the cop- cation could still be achieved. The results as a futures trader on the Sydney per surface can be observed against the are shown in TABLE 5. GP Futures Exchange, where his ASTM copper strip test standard back- success led him to a position ground. After treatment with the system, NOTES with Chemical Bank in London. a the copper strip test results were consis- Exion Systems Mr. Crowe's sales and trading experience eventually b Exion LT led him to Singapore, where he transitioned to oil tently 1a or 1b. The system was capable of c Exion LT-200 and gas and formed No Heat Resources, a chemical treating the butane stream with different d Exion LT A-700 treating company. Mr. Crowe's experience in sulfur levels of copper strip tests results (4, 3 or treating later prompted him to relocate to Texas, where he helped form Exion Systems. Mr. Crowe is 2) and consistently providing 1 results. REFERENCES 1 Stewart, M. and K. Arnold, Gas Sweetening and also Managing Director of NH Resources. He holds In addition to passing the copper strip Processing Field Manual, 1st Ed., Elsevier, October a BS degree in commerce from the University of tests, the process can reduce the mercap- 2011. Canberra in Australia. Electronic and single printed copies for distribution with permission to Nexo Solutions from Gas Processing January/February © 2020 Gulf Publishing Company