Rentech Nitrogen Partners LP, a Rentech Inc. spinoff, on Wednesday announced the launch of an initial public offering that could raise roughly $300 million.

Rentech Nitrogen was formed in July by the Los Angeles alternative energy developer to own, operate and expand its companion nitrogen fertilizer business. Its assets include a nitrogen fertilizer facility in East Dubuque, Ill. that produces anhydrous ammonia and urea ammonium nitrate solution used in Midwest farming operations.

Its parent company, which trades on the NYSE Amex Exchange, is developing cleaner burning jet fuel made from plant-based biomass.

The offering will be for 15 million common units, with an anticipated price of between $19 and $21 per unit.

The units represent limited partner interests. Rentech Nitrogen, which booked $176 million in revenue for the 12 months ended June 30, plans to list its common units on the New York Stock Exchange under the symbol RNF.

The underwriters, led by Morgan Stanley & Co. LLC and Credit Suisse Securities, have a 30-day option to purchase up to 2.25 million additional units at the IPO price to cover any overallotments.

After the IPO, Rentech Inc. will indirectly own common units that represent about 60 percent ownership of Rentech Nitrogen. If underwriters exercise the entire overallotment option, that stake would be reduced to about 55 percent. Rentech Inc. also will own 100 percent of the non-economic general partner interest in Rentech Nitrogen.

Rentech Inc. shares closed up 22 cents, or 18 percent, to $1.42 on the NYSE Amex Exchange.